[Android Q&A, Help & Troubleshooting] smokeyou:
Working backup method below. This took a bit of time to figure out - enjoy!

Initial Steps

1. Enter EDL mode - Power + Vol Up + Vol DN

- Sonim logo will flash briefly followed by a blank screen

- Device reflected as Qualcomm HS-USB QDLoader 9008

2. Load Sahara FH programmer

QSaharaServer.exe -p \\.\COM15 -s 13:prog_emmc_ufs_firehose_Sdm660_ddr.elf

3. Open notepad and copy XML data below

(Save alongside fh_loader.exe)

XML covers critical system data only!

Userdata and device specific (EFS) partitions are not covered.

<?xml version="1.0"?>
<!--NOTE: This is an ** Autogenerated file **-->
<!--NOTE: Sector size is 512bytes-->
<data>
<program start_sector="24286840" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="abl_a" filename="abl_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="24288888" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="abl_b" filename="abl_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="131072" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="7168" label="xbl_a" filename="xbl_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="138240" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="7168" label="xbl_b" filename="xbl_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="145408" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="8192" label="tz_a" filename="tz_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="153600" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="8192" label="tz_b" filename="tz_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="161792" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1024" label="rpm_a" filename="rpm_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="162816" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1024" label="rpm_b" filename="rpm_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="163840" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1024" label="hyp_a" filename="hyp_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="164864" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1024" label="hyp_b" filename="hyp_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="165888" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1024" label="pmic_a" filename="pmic_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="166912" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1024" label="pmic_b" filename="pmic_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="24294024" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="66848" label="splash" filename="splash.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23592960" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="keymaster_a" filename="keymaster_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23595008" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="keymaster_b" filename="keymaster_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23597056" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="cmnlib_a" filename="cmnlib_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23599104" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="cmnlib64_a" filename="cmnlib64_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23601152" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="cmnlib_b" filename="cmnlib_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23603200" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="cmnlib64_b" filename="cmnlib64_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23605248" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="8192" label="mdtpsecapp_a" filename="mdtpsecapp_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23613440" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="8192" label="mdtpsecapp_b" filename="mdtpsecapp_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23621632" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="65536" label="mdtp_a" filename="mdtp_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23687168" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="65536" label="mdtp_b" filename="mdtp_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23752704" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="225280" label="modem_a" filename="modem_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="23977984" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="225280" label="modem_b" filename="modem_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="393216" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="131072" label="boot_b" filename="boot_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="262144" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="131072" label="boot_a" filename="boot_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="24718360" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="devcfg_a" filename="devcfg_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="24720408" sparse="false" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2048" label="devcfg_b" filename="devcfg_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="524288" sparse="true" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="8388608" label="system_a" filename="system_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="8912896" sparse="true" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="8388608" label="system_b" filename="system_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="21495808" sparse="true" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1048576" label="oem_a" filename="oem_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="22544384" sparse="true" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="1048576" label="oem_b" filename="oem_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="17301504" sparse="true" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2097152" label="vendor_a" filename="vendor_a.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
<program start_sector="19398656" sparse="true" readbackverify="false" physical_partition_number="0" partofsingleimage="false" num_partition_sectors="2097152" label="vendor_b" filename="vendor_b.img" file_sector_offset="0" SECTOR_SIZE_IN_BYTES="512"/>
</data>

Backup

Save emmc data to local target file(s)

fh_loader.exe --convertprogram2read --port=\\.\COM15 --sendxml=Backup.xml

Restore

Follow same steps while removing --convertprogram2read.

fh_loader.exe --port=\\.\COM15 --sendxml=Backup.xml

Using the original XML, fh-loader will crawl the working directory for file names corresponding to each entry.

Disclaimer:

- Do not modify backup files.. Or at least take great caution when modifying! It's not my fault if you break anything.

Carrier Switching / Root

Carrier switching would likely work given a full image.. I personally only have AT&T devices. It works fine on GoogleFi already and with all pre-loaded Sonim management tools / carrier bloat removed, it's a truly great near-ASOP experience. So i'm content.

Root has been achieved in test! Coming soon to the XP8 root thread! Just need full system images of various build versions to use for root method validation - thus my interest in providing a solid backup option :).