Means of controlling the battery charge voltage limit on Bangle.js 2?

The Chargie seems very cool. Thanks for dropping that name […]

Sure thing! I'm glad mentioning this was helpful.

As for the Bangle, a workaround would be charging from a powerbank. Many of those cut off the charging when the current is low. […]

My pre-2013 powerbank does this and it has bugged me so much. Now I see that this is a feature! I've got a USB power meter that can be independently powered (so it won't increase the power bank's load) - next time I need to charge my Bangle 2, I'll see how it goes.

I'd be really surprised if someone hasn't made an inline USB gadget that does that already - but if not you should totally make one!

Ah, that's actually why I mentioned Chargie - see "Is there any way Chargie can work without the app?" on the FAQ page.

Chargie was originally intended for managing phones via iOS and Android, but it also supports a hardware cut-off that's committed to memory. Granted, there are probably ways to make a cheaper circuit if you don't support Bluetooth control and all that.