The .ttf version should be usable as-is in Godot, without any custom code. I've used it myself in both Godot 3 and 4 projects. What issues are you having?
the ttf distorts when you need to change up resolutions. Godot is very picky about that thing and requires the ".png + .fnt" file to work. In order to make it work with JSON, it needs custom code to be written in order to extract all thie data from the JSON to correctly work. Doable, but a pain to do when in need of doing something fast ^^''