Of course they do, you can file a request so they would send you what info they hold. I did so. They store everything - your every message, all login dates, device metadata and anything else you can think of.
The best part? They say that the messages you send are like email, so they are not obliged to delete them.
On xiaomi blog they mentioned it will not get MIUI 15.
I've got zero expectations, they made POCO F3 and F4 with same SoC but F3 is EOL, and F4 still gets updates.
Considering they neglected it in ideal conditions, how can we believe them to support less convergent set of devices?
Anyway, anyone can tell me why should we care about Android updates except for security? I'm totally bored by Android 14, not even one interesting thing in release notes. Maybe taking sharing menu out of OEM hands and updating it through Play Store, but seeing how they did something like that in Chrome makes it rather intrusive feature.
MIUI is even more boring, from MIUI 11 to 14 on POCO F3 I have noticed no changes in the skin, they added widgets for China-only but these see useful, just nice to look at. I love widgets, but c'mon.
Wouldn't it be MIUI without a coat of paint, considering this is their plan B system without or with limited Google services?