Wrote a Go compiler in Java, used it to compile this JVM implementation written in Go

Great, now just use this JVM to run your compiler :)

Ouroboros

Lambda the ultimate

Well, you'd probably get pretty good perf with graalvm truffle, but certainly the building blocks of golang shouldn't be that problematic to implement in java given that the go language model is more straight-forward IMHO. I wouldn't assume it'd beat pure golang compilation but who knows.