You can remove all notifications.

I have done so with all my devices since ~15 years ago. It's incredibly refreshing. When I see others reacting monkey-style to any notification or vibration from their phone or watch, I secretly smile inside.

I have a $20 smart fitness watch from Amazon which I use for sleep tracking, though it's a pretty capable watch. Much smaller than an Apple Watch and the battery lasts like 10 days on a charge. It connects to Apple Health and puts the heart rate / fitness / steps / sleep data in there.

If it could do the "make my phone beep" feature I'd probably switch to it as my main watch. But of course that's Apple exclusive proprietary :(

I think they really need a separate product that can have no screen or a minimal screen and ditches the need for app compatibility. Just selling the Apple Fitness features without the screen for apps would provide a lot of value and let them play with form factors and lower price points.