There are two other WebTorrent implementations (possibly more that I don't know about!)

* https://github.com/anacrolix/torrent (Golang)

* https://github.com/arvidn/libtorrent (C++)

An implementation in Rust would be amazing, but there is a quite a bit of work to make that happen in pure Rust though! If you want to use FFI/unsafe code it is totally do-able :)