redmi note 9 pro user here. Now on LOS. The default OS is full of telemetry. Even the calculator wants you to agree to personal data being used. Would avoid unless you only want the hardware and the model you want has active community rom support.
Also the Bootloader unlocking process is a PITA. You need a xiaomi account logged in to the phone for it for 2 weeks, then they may allow unlocking the BL but only through their unlocker app that frankly sucks. You may have to sit through the wait period twice if something goes wrong. Ask me how I know.
Aw man, every midrange phone that would be interesting comes with MediaTek SOCs. I should check if the custom rom scene is still dead for phones with MT chips… Do they still withold the sources needed for rom developement?