If you are okay with Rust or C# idk why Go is an issue? Go powers most infrastructure on the internet that we rely on. Docker, Kubernetes, Hugo, Caddy, MinIO, a lot of these are used in backend services so you would never even realize you are using them but you are. I think Go is fine.

I'd prefer Rust as well, but anything with a decent type system is okay. I have bad associations with Java software, but idk if that's the language itself, or enterprise brainworns.

Go is fine, but I prefer Rust and C#.

Rust, C#, Java, Go and maybe even Erlang would suffice for modern stack and IO heavy and performant workloads.