Hey Dorothy - welcome!
I can't offer any semi-integrated battery wisdom (I have a 2-yo MiniST2 with the older battery design), but I agree about that little bell thingy. However, I didn't replace it, I supplemented it. The quiet little bell is actually ideal for a discreet non-scary alert on a quiet woods trail, otherwise useless.
For louder beach trails and most streets, I added another bell very similar to this one next to it:
https://amzn.to/3TlMUxv - it's a very well-made and loud mechanical dinger.
For cutting through a rolled-up car window, I also added this:
https://amzn.to/3yJm74G - incredibly annoyingly loud and lasts months on a charge unless you find need to use it all the time.
So yes, I have three things to reach for, but it's nice to have options. If you consider something similar, be sure to check your handlebar for mounting space - Rad bars vary and some have a very short straight section next to the grips. My pic below illustrates the two new bell controls just to the right of the Rad control buttons; it's tight but it works and requires minimal hand movement to hit any of the three. The electrical bell has a very small remote button with a pigtail connected to the main noisemaker, so it's pretty easy to find room.
Hope you get some comforting battery feedback; we have a number of batt experts here.