Although it seems like a long shot, Android 11 works fine on the Xiaomi Mi A1. The POSP ROM might not be perfect but looks very good and seems stable enough for daily use. The version that I installed on my handset comes with the January 5 security patch, and it also seems to support Qualcomm aptX.
https://www.notebookcheck.net/Android-11-on-the-Xiaomi-Mi-A1-via-POSP-Not-perfect-but-good-enough.515484.0.html
So many good ROMs out there and you chose this "POSP" -- a mostly unknown custom ROM, without any reputation built over time.
Not that many based on Android 11 available yet, and even YET unknown ROMs deserve a chance, don't you think? I am open for suggestions, so tell me which one to choose next? I got my sights on crDroid. Version 7.2 is based on Android 11-based LineageOS. :)
For Android 11, I'm highly suggest for Pixel Experience (stable) or CrDroid (stable and alot customization).
Pixel Experience is apparently not stable on Android 11 yet (https://download.pixelexperience.org/tissot). crDroid is the next in line, as I said earlier. Unfortunately, it looks like the capacitive buttons do not lit up on most of these Android 11 ROMs, although they seem to work (they work on POSP, for example, but never light up).
Thanks for the review, very informative. I'll keep an eye on your experiments as I've just bought a second-hand A1 as my main device (south american aftermarket is huge and necessary ;) )
Cheers!
I am glad you enjoyed it, probably tomorrow I'll post about my experience with crDroid, which I think I'll keep on the Mi A1 from now on... but maybe I'll give others a chance in the future as well.