You can check Jujutsu—a version control system from the link: https://github.com/jj-vcs/jj
It's written in Rust. It started as a hobby project of one of the Google Devs and now is used within Google as well. And it's open source

Although I can't say it's an complete alternative to Git or Piper, still it has some improvements over some git features. You can also check this short youtube video which gives it's overview: https://www.youtube.com/watch?v=cZqFaMlufDY