there is a crate called steamloacte (https://crates.io/crates/steamlocate/) which can easily find steam library folders, and even a specific app like resonite, though this library has some known bugs in it's current latest release and I'd probably wait until they release 2.0.0 (which they probably will soon, considering there is already a beta version)