Rust/wasm app using a git library on a browser filesystem

I'm looking for advice on how to build a web app using Rust which will extend git functionality (adding support for issues and PRs in the project .git directory), alongside a solid git library for standard git operations on the same .git directory.

My first thought was Emscripten, because I thought this might make it easy to use a non-Rust git library share the same filesystem as my new Rust git features. For example using wasm-git (libgit2 compiled to wasm by Emscripten), but I'm getting the impression Emscripten and Rust don't play well together.

So can I do this using wasm-pack and target wasm32-unknown-unknown? Or is emscripten feasible? Thanks.

What Web-Filesystem API do you want to use?

My last research yielded nothing usableā€¦

Anything POSIX like with a memory fs for testing, and where I can implement my own when I'm ready to do that. I haven't looked recently but I thought there were candidates for this in Rust, certainly for JS.