Different character sets for BangleJS 2

Greetings from Russia! My device has finally arrived and I'm having a lot of fun with it.

One immediate issue that I noticed is lack of Unicode support for notifications. It's understandable that full Unicode character set is infeasible (both support and fonts). However, there are also known local character sets, like ISO8859-5, CP1251 or KOI8-R for Russian.

I was wondering how complex would it be to:

• Replace font in Messages with one containing Russian letters on expected code points for one of the encodings above;
  
• Add Gadgetbridge support to encode strings as expected.
  
  

Where should I start with this on BangleJS side? Can I somehow make font in Messages customizable and configurable from app store? Ideally one would upload a desired font separately (or just use the system one), and then select needed encoding in Gadgetbridge settings.