[Google Pixel 2 XL ROMs, Kernels, Recoveries, & Oth] GROOVYJOSHCLARK:
You'd be much better off just following the steps the dev provides as they are usually tested and work as they are intended to work for this ROM and are accurate. I personally prefer to ALWAYS wipe the device with the factory image after any ROM change (LOS to AOSiP, or AOSiP to LOS, ETC) or with any major version changes (9 Pie-->10 or 10-->9 Pie, ETC) as that way I know all partitions are laid out exactly perfect per Android's specifications (as well as the more important VENDOR partitions for all hardware specific drivers). You have to make sure your internal SD is copied to the PC as well as backing up all TXT AND MMS first (Google doesnt backup/restore MMS - ONLY TXT).

This is my exact process and it works every time for 9 or 10 (*****BACKUP EVERYTHING PRIOR USING SOME TYPE OF TXT/MMS BACKUP SOFTWARE PRIOR*****):

First backup your TXT/MMS using SMS Backup and restore or anything that handles MMS as well. Use your choice of software for backing up messages, whatever you feel comfortable with using (SMS Backup and Restore saves to XML on internal SD storage) so that's why I prefer it (I own premium license but free works the same, just ad-free). Then you copy the entire SD FROM your internal storage (SD Card emulation) to a location on your PC or MAC/Linux that has enough space to hold the entire amount use. When you copy the entire contents of your internal SD to PC, this will include your SMS Backup XML data (assuming you stored on the internal SD which you will). This will keep your data and messages safe so you know you will have your messages stored safely to use later under the new Android ROM/OS. Then using the correct factory image from Google (whatever the ROM dev says to use in the install notes), or you can extract the metadata from ROM.zip\META-INF\com\android\metadata using notepad (look for this line post-build=google/taimen/taimen) whatever comes after the : is the firmware this ROM requires. I then wipe the entire device on BOTH slots (fastboot --set-active=a first then flash and wipe firmware, then redo fastboot --set-active=b and wipe that slot as well, I.E. repeat the same flash -wipe process on both slots), once both slots are flashed and wiped, boot once into stock OS, skip EVERYTHING (pin, google account/ everything), reboot to bootloader, push TWRP to boot (but I do not ever install TWRP anymore, I just fastboot it whenever needed for installs or updates), then follow the steps. These steps are the same as the dev provided steps, but I add in a /format instead of a erase user data (as I found it works better) but the steps do not include a method to push or move the ROM zip to the SD so once you format or erase user data, you lose the ROM zip), that is added to my steps:

Swipe to Factory Reset

I also FORMAT /data then factory reset again, then reboot bootloader, load TWRP from ABD, and format /data again

adb push ROM.zip /sdcard (SD will be wiped and deleted once you format /data)

adb push GAPPs.zip /sdcard

Flash the latest build of ROM

Reboot to bootloader, push (boot) TWRP recovery (from ADB)

Flash GAPPs (IF NOT INCLUDED IN ROM)

Flash a custom kernel (optional)

Flash Magisk zip (optional)

Reboot to system

Configure the system per your taste (apps/settings/customization), I prefer not to install MAGISK from recovery (during the install) but instead I patch the boot.img from within TWRP then ADB flash the boot.img to the boot partition from the bootloader, then boot into OS this time with ROOT (MAGISK patched it with ROOT). Then I install EX kernel and flash the kernel and rebuild all my apps, and settings, then finally I use SMS Backup and Restore to restore all of my messages. NOTE I airplane mode during the restore so no new texts come in during the time and are lost, this has happened to me on older Android OS restores so keep it in mind.

Again, this method works for me flawlessly across the board for 9 or 10 ROMs, and I seem to have one of the funky Pixel 2XL's that error'd out any other method I tried or tested. I would either bootloop, or loop to recovery but never the OS until I firmed up these steps and now its the only process I use. I test all ROMs and firmware so I wrote these steps from months of user testing different scenarios and ROMs, this seems to work flawlessly across the board, but take it with a grain of salt. Not all users are willing to put in this much time and effort, but if you do, I promise it WILL work for you perfectly (assuming you followed every step correctly).