Source is here:
https://github.com/TakWolf/retro-pixel-font
Adding characters is very simple.
All the glyphs are ‘.png’, for example:
You just need to add a image here, that is!
Even, you can fork this project, and use this action
https://github.com/TakWolf/retro-pixel-font/blob/master/.github/workflows/release.yml
to automated build!
I don’t have much time to deal with it at the moment, but please feel free to leave me a message if you have any questions!