Just an update, I could not find any info on android 9 breaking the sensors anywhere. Whatever the issue is, it must only affect a small number of phones.
Got another pixel 3a, flashed 9, sensors work! Installed Ubuntu Touch and sensors work! UT looks amazing on this phone and I have not had to charge it in 24 hours! Still have to test everything out such as MMS.
As for the original phone, as it works on 11, I gave it to a family member who needed a new android phone.
Man, Ubuntu Touch is getting expensive 😉