A web app i have to host on my own, use workaround apps to connect to it vs a clunky casio app that just works? I’ll go with clunky here

You make it sound like rocket science or huge bother.

If you're a hacker/dev/tech nerd, that's trivial. You do similar things twice before breakfast without thinking about it.

I use this app on android : https://f-droid.org/en/packages/org.avmedia.gshockGoogleSync...

I mean... this is Hacker News. A lot of the audience would be excited about an self-hosted alternative.