NextDNS has presets to block OS tracking, this is different from just Ads. Any DNS with variable blocklists can use these. There is a windows one, but not sure about Xiaomi.
You dont need google services to use Aurorastore. It works currently.
Also try creating a shelter profile and then disabling the play services using adb in the main one with
Google play services spy on everything with privileged permissions (all) as they are system apps. On GrapheneOS you can install them as regular user apps, and they still work.
I recommend Mull from F-droid instead of firefox. Try adding my custom addon collection: