I just had my screen replaced on my Google Pixel 6 Pro this morning and encountered the issue where my fingerprint sensor needs to be enrolled and calibrated.
I followed the instructions to use the Google Tool and on the first time after completing Google's installation and restart of my device while plugged in on fast boot mode, it didn't work.
I tried again, placed my phone on fast boot mode, plugged my phone to connect to my laptop to access the tool via browser and it installed it again and restarted my phone.
What I did differently this time was read what was on the webpage, it says to restart my phone again to finish calibration (after Google restarted my phone, I restarted it again)—now it works.
I am not sure if this is a stroke of luck or a step people missed because Google already restarted for you. Perhaps a UX/copywriting issue on the processes detailed on the screens.
In any case, maybe others may verify.
PS another thing to note when doing screen replacements is that do not forget to remove the protective film on the replacement screen that mates with your camera, I experienced this and thought my front camera was broken as it was just showing a black screen.