user since last Christmas I wanted to give feedback to share the difficulties, successes and some tips.
Especially if I'm wrong, don't hesitate to correct me the goal being to give reliable information to make life easier

GPS: I learned that with waydroid active the gps does not work.
solution to test it quickly:
https://forums.ubports.com/topic/7047/gps-not-working-on-redmi-note-9s/17

Waydroid: works well, be careful on this smartphone do not install it with waydroid-helper but directly (in OTA-20 perhaps in OTA-21 there's no problem, I don't test).

Bluetooth: works well except for phone calls (music videos browser youtube ok).

Dekko2: email attachments not accessible

Axolotl: too much bug to use it (duplicate messages in groups, capricious synchronization on my phone,) I use Signal with Waydroid without problem.

for the rest, smooth browser, battery life slightly less good than under android (especially if several android apps open I have the impression that there is a battery leak). Otherwise 24h without problem in heavy use.

With some sacrifices (missing some native apps) my daily use is for the moment assured in a pleasant way.

Edit : for installation there are some error, the easiest way is to have the last android 10 official MUI firmware on the phone before use ubports installer. Then everything work fine.

Thanks for your time, finally I factory reset, and then I install waydroid without waydroid helper.
And it works.

I really think waydroid helper make apt-update AND apt-upgrade and complicate everything (it's my point of view ).

Then android app works UT app works. last thing (but not here) gps if I solve that too I 'll make UT my only main phone

(Happy new year anyway )

I can't reinstall without wipe there's too much issue on Xaomi redmi note 9S.
(error 1 error 126 etc. bad repertory, bad rights I think).

Only way ton install UT is :
Install MUI officiale firmware (Android 10 not 11) so totally wipe UT
then use ut installer: and it works nice