Comment by trnglina

Please educate me if I'm missing something!

From memory, what I would do is simply download the original ttfs or otfs, run them through woff2 (https://github.com/google/woff2), and then write the @font-face declarations for each weight/style variation. Variable fonts make this even easier, since you can get by with just the one declaration.

One could further optimise them for size with fonttools, to do stuff like subsetting by unicode ranges (https://github.com/fonttools/fonttools), but that's quite optional. Unless your font includes CJK, it's probably not that big to begin with.