[Moto G5 Plus Guides, News, & Discussion] bra1niac:
Well, from an adb shell on my never unlocked G5 plus, I can see:

1|potter:/dev $ mount
rootfs on / type rootfs (ro,seclabel,size=1737968k,nr_inodes=154645)
tmpfs on /dev type tmpfs (rw,seclabel,nosuid,relatime,size=1843448k,nr_inodes=155161,mode=755)
devpts on /dev/pts type devpts (rw,seclabel,relatime,mode=600)
proc on /proc type proc (rw,relatime,gid=3014,hidepid=2)
sysfs on /sys type sysfs (rw,seclabel,relatime)
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,seclabel,relatime)
none on /acct type cgroup (rw,relatime,cpuacct)
tmpfs on /mnt type tmpfs (rw,seclabel,relatime,size=1843448k,nr_inodes=155161,mode=755,gid=1000)
none on /dev/cpuctl type cgroup (rw,relatime,cpu)
pstore on /sys/fs/pstore type pstore (rw,seclabel,relatime)
/dev/block/dm-0 on /system type ext4 (ro,seclabel,relatime,discard,data=ordered,inode_readahead_blks=8)
/dev/block/bootdevice/by-name/cache on /cache type ext4 (rw,seclabel,nosuid,nodev,noatime,data=ordered)
[B]/dev/block/bootdevice/by-name/persist on /persist type ext4 (rw,defcontext=u:object_r:persist_file:s0,seclabel,nosuid,nodev,relatime,data=ordered)
[/B]/dev/block/bootdevice/by-name/dsp on /dsp type ext4 (ro,seclabel,nosuid,nodev,relatime,data=ordered)
/dev/block/bootdevice/by-name/modem on /firmware type ext4 (ro,context=u:object_r:firmware_file:s0,nosuid,nodev,relatime,data=ordered)
/dev/block/bootdevice/by-name/fsg on /fsg type ext4 (ro,context=u:object_r:fsg_file:s0,nosuid,nodev,relatime)
adb on /dev/usb-ffs/adb type functionfs (rw,relatime)
/dev/block/bootdevice/by-name/oem on /oem type ext4 (ro,context=u:object_r:oemfs:s0,nosuid,nodev,relatime,data=ordered)
tmpfs on /storage type tmpfs (rw,seclabel,relatime,size=1843448k,nr_inodes=155161,mode=755,gid=1000)
/dev/block/dm-1 on /data type f2fs (rw,seclabel,nosuid,nodev,noatime,nodiratime,background_gc=on,discard,user_xattr,inline_xattr,acl,inline_data,nobarrier,extent_cache,active_logs=6)
/data/media on /mnt/runtime/default/emulated type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:1015:660:771,derive=multi,noconfine)
/data/media on /storage/emulated type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:1015:660:771,derive=multi,noconfine)
/data/media on /mnt/runtime/read/emulated type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:9997:640:750,derive=multi,noconfine)
/data/media on /mnt/runtime/write/emulated type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:9997:640:770,derive=multi,noconfine)
/dev/block/vold/public:179,65 on /mnt/media_rw/10CE-8F95 type vfat (rw,dirsync,nosuid,nodev,noexec,relatime,uid=1023,gid=1023,fmask=0007,dmask=0007,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro)
/dev/block/vold/public:179,65 on /mnt/secure/asec type vfat (rw,dirsync,nosuid,nodev,noexec,relatime,uid=1023,gid=1023,fmask=0007,dmask=0007,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro)
/mnt/media_rw/10CE-8F95 on /mnt/runtime/default/10CE-8F95 type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:1015:660:771,derive=public,confine)
/mnt/media_rw/10CE-8F95 on /storage/10CE-8F95 type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:1015:660:771,derive=public,confine)
/mnt/media_rw/10CE-8F95 on /mnt/runtime/read/10CE-8F95 type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:9997:640:750,derive=public,confine)
/mnt/media_rw/10CE-8F95 on /mnt/runtime/write/10CE-8F95 type esdfs (rw,nosuid,nodev,noexec,relatime,upper=0:9997:640:770,derive=public,confine)

attempting to rip the persist partition and write it to my external SD card however:

1|potter:/persist $ dd if=/dev/block/bootdevice/by-name/persist of=/mnt/media_rw/10CE-8F95/persist.img
dd: /dev/block/bootdevice/by-name/persist: Permission denied

similarly

2|potter:/dev $ cd /persist
127|potter:/persist $ ls
ls: .: Permission denied

So, without root I'm not sure I can get the image out. So I believe we need someone who has unlocked their bootloader and rooted their phone without ever flashing a custom ROM to do the above.