hi! assuming you're talking about the default Latin/Cyrillic script fonts (JP/CH/KOR are off-the-shelf fonts you can find by googling their names! which can be found in the fonts folder), there's not really a ready-to-use version of the font files, as they weren't made as "font files" in the first place (with an exception that, depending on what you're looking for, might actually be good enough for you!*) - they were hand-drawn as a bunch of pictures and assembled together in a way that's optimized for use in game; you can find them in Mosa Lina/fish/game/res/fonts under names Test-Regular and wombatfont, but it'll probably be very difficult to use them unless you manually convert them into like a .ttf (i used this tool at some point for a diff project! https://yal.cc/tools/pixel-font/ )

* the exception is that there's an old version of the font that's used for displaying Help texts in a .ttf format! we've added a lot more glyphs since then, but the uppercase version of the English alphabet is all there - you can find it by Right-clicking the game in your Steam Library -> Properties -> Betas -> select pre-collabaration; once it's downloaded, go into the game's folder, rename package.nw into package.zip, extract it and you'll be able to find the .ttf in a fonts folder

using it for non-commercial stuff is generally cool w/ us :)