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 recommend checking out Gadgetbridge. It is an open source app, with no network permission requirements, that replaces the OEM app for a large number of watches. I’m running an Amazfit GTS 4 with it and it has been almost flawless.