GPL-licensed Gadgetbridge for Android [1] allows syncing various fitness trackers to your phone without internet connection
I use this with a lenovo WatchX and it works well. It is pretty basic so you can join the party and hack if you feel it. WatchX is very cheap. ~USD $30 on aliexpress.
I would not ever go near the lenovo watch android app which I consider to be on par with radioactive toxic waste.
Using gadgetbridge & Watch X is superior to the Apple Watch & ecosystem at about 1/10th the cost. Recommended.
I wonder if I can buy a second hand miband and get around that.
Search for huami-token on github or for Huafetcher (android version of the same) on Codeberg.
And read our wiki
Disclaimer: I did the Kivy wrapping of huami-token for Android.