Amazfit with Gadgetbridge.

I bought one a couple of years ago and it works great. Gadgetbridge keeps all the smart functionality local to your phone.

I’ve heard good things about the Garmins as well which I think are mostly also supported in Gadgetbridge.

I’d second the recommendation for Gadgetbridge and would add most of the Amazfit watches to the list. I have the Amazfit GTS 4 and it has run flawlessly with Gadgetbridge.