I personally prefer Agda to Lean or Coq [1] to prove my theorems but this frontier is imho among the most exciting research in theoretical CS in many many decades. I really wish more programmers and mathematicians knew about automated theorem proving and automated reasoning. It's nothing short of revolutionary and I think next generation of pure mathematicians will use these as a crucial tool in their research.
[1] It's a personal preference but Agda is simply a much better language with almost limitless metaprogramming which allows me to write proofs close to as they'd appear in prose math papers. It has a smaller ecosystem though. I've never seen a proof in any other language I personally didn't think would be much more readable/simpler in Agda.
I'm currently creating an interactive tutorial on Agda, with lots of embedded exercises (running purely in the browser/on a server, no installation required), perhaps it is useful to some:
Oh, really? I'm curious what exactly you mean by limitless metaprogramming. I've really been drawn into Lean specifically because of how easy to extend and malleable the language itself is, so if Agda is even more so then I'd be really eager to try that out.
[1] It's a personal preference but Agda is simply a much better language with almost limitless metaprogramming which allows me to write proofs close to as they'd appear in prose math papers. It has a smaller ecosystem though. I've never seen a proof in any other language I personally didn't think would be much more readable/simpler in Agda.