Some answers for my xiaomi exerience with global ROM.
To change wallpaper or deafult ringtone you need to consent for data harvesting. I am using custom luncher no problem. There are couple of very annoing bugs: reboot messes the layout of quick actions. Sometimes open apps are missaligned. Battery optimization is so bad that sometimes my timer won’t ring to remind me that my laundry is ready. I had overslept couple of times due to this. Xiaomi really pushes for their native video, gallery and app store but it doesn’t prevent from changing the deafults.
I also got bad QA and audio DAC was broken for me.
I don’t use assistant but it always pops up and wants my attention
G maps works good and links to google play open in google play.