Second this, my wife and I both got one. It's a slight inconvenience to get the Authorization key from a command line, but it's not very difficult. Gadget Bridge basically fakes the phone side of the app, which means it won't send your data out and watch thinks everything is fine and normal. Pretty cool. Look at all these free watch faces: https://amazfitwatchfaces.com/
I tried reading the gadget bridge instructions for my watch. Could not get a straight answer on getting the authorization key (I'm a noob), wasted 2 hr. o3 gave me perfect instructions that got it done in 20 minutes. Ya win some ya lose some.
I had the same concern so I actually just bought a used newer pixel and started a fresh install of Graphene. It took me several weeks to learn how it works and migrate my accounts and switch to FOSS apps wherever I could.
Second this, my wife and I both got one. It's a slight inconvenience to get the Authorization key from a command line, but it's not very difficult. Gadget Bridge basically fakes the phone side of the app, which means it won't send your data out and watch thinks everything is fine and normal. Pretty cool. Look at all these free watch faces: https://amazfitwatchfaces.com/