I'm maintaining Delta and trying to help out a bit with Eglot -- an Emacs LSP (Language Server Protocol) project, and trying to improve my Rust and Lisp along the way. LSP in Emacs with Eglot is fantastic (especially for Rust, but also Python. Those are the only ones I've tried so far.)

https://github.com/dandavison/delta

https://github.com/joaotavora/eglot