checking for firmware version

Well, if it works then I guess that's fine. It doesn't have to be too speedy.

If at all possible I'd check based on the actual feature though? I mean, if you need Bangle.isGPSOn then check for Bangle.isGPSOn!==undefined.

You could maybe also do something like turning 2v08.123 into 2.080123 and could just compare based on that? You just need to ensure you pad out the number after the '.' correctly.