Interesting question, from my understanding Pathfinder is only concerned with rendering so it doesn't completely replace FreeType: you still need some software to extract the curves path data from the font file. This can be done in rust with skribo and font-kit

You can check out this issue for more info: https://github.com/servo/pathfinder/issues/143

Pathfinder replaces FreeType. It doesn't do more, and shouldn't: it's focused on glyph (and image) rendering.