Wear OS watches commonly have wifi, and can be programmed with the standard Android API and toolchain/IDEs. I doubt that Google will discontinue Wear OS - although your evaluation of risk will undoubtedly depend on whether you're looking at developing personal or commercial apps.

I'm currently wearing a TicWatch Pro 3 Ultra, which has wifi, Bluetooth, and GPS. I've written personal tools for it, and its fairly painless (and free). As a developer with some background in Android, I enjoyed the experience. Getting apps approved for the app store is a pita though, as Google sets quite high bars for the review process.

I also have a Samsung Galaxy Watch4, which also has wifi. People here speak well of Pebble, which might be an option, but I have no real knowledge of it.

Finally, though, wifi is power-hungry and watches have limited batteries and endurance. Both Wear OS and WatchOS will limit wifi use by apps to conserve power, and you ultimately can't do much about that. Using Bluetooth to a phone, and its much greater wifi capacity, is a common approach.