If you’re comfortable with a bit of setup, there are open hardware options on the market. They’re reasonably basic compared to a flagship but phone notifications, some health metrics and telling the time are all quite possible.
PineTime (with Infinitime firmware)
If you want to basically make it from scratch there’s also the Yatchy
From a quick search, “sleep as android” seems to have support for both, although people have varying success with it