Unfortunately, transpiling has a huge bunch of problems, which you can see in for example how quickly nim vs crystal compiler matured - even though the crystal compiler is more complex. I'd be interested in seeing go's stdlib, ssa backend, and toolchain turned into a robust library. Like LLVM but including a GC, a stdlib with a CSP implementation, and a complete toolchain for static compilation.
Go does have a buildmode for c-archive and c-shared, but it's built around the hobbled Cgo, so you have to explicitly export funcs, and things like structs cannot be exported. Still, a swig-like shim/bridge could be developed, but I am unsure at what cost (I think the go mobile stuff does a form of this).