Ok guys. So small wrap up, before I get to the next problem.
I got the Pixel 2 XL and use adb as well as fastboot over Ubuntu 18.04.
Preparing the installation and flashing, I downgraded the phone to Android 8.0 from the Google factory images and I followed the whole bootloader unblocking procedure in the manual. I booted into TWRP with fastboot boot path/to/twrp.img and followed the rest of the manual. From here I went two ways:
a. following the rest of the manual, however sideloading stops at (~47%) until finishing. However after step 2/2 the shell on the phone says Unable to find partition for path ‘/cache’
b. uploading the .zip file from /e/ with adb push eOsimage.zip and installing it under TWRP’s install.
If I go into TWRP system reboot, I already get a warning, that no OS is installed. I also used the vbmeta partition, like suggested in this forum thread here, leading to this xda-developers article, but honestly I don’t know when and where within the procedure I should do this.
@archje, the first post you have shared gives a hint on how to install /e/ on the Pixel 2 XL, but honestly I am so confused by the multiple references and that the procedure is not once explained properly.
I bought the cellphone especially for the reason to flash it with /e/ yesterday. I would have gone with another phone otherwise. It took me the whole day to see, that the proceeding from the manual is probably not as straight forward as it looks like and that barely anyone - except for wilson in this thread - made it to install /e/ on this phone. Has anyone ever made it to install /e/ on Pixel 2 XL from the the manual? I am not far from giving in 