I am back to using Expo and React Native, for three reasons: 1) Expo is an easier way for me to generate apps for both Android and iOS, 2) I'm familiar with React and React Native, and 3) I actually got an app to work, and there may be hope yet.

I had success getting a sample project to work with this post: https://blog.theodo.com/2023/07/ble-integration-for-rn-apps/

Long story short, I did not use EAS to make a package then use on my phone, I used USB debugging. It didn't QUITE do what I wanted, but 1) it didn't crash and 2) once I manually turned on bluetooth on my phone, it popped up the bluetooth selection menu. I also had to use Node 16 due to this setup using an outdated SSL setup.

I also found this blog post on the Expo web site I'm going to try to get working: https://expo.dev/blog/how-to-build-a-bluetooth-low-energy-powered-expo-app

The main goal is to make an Android app (for now) that connects via bluetooth to my homemade smart watch.