If “build the server and client in the same language” is a hard requirement, I believe your only choice is JavaScript…

The tone of the post makes me think you’re newer to programming, so I’ll leave it at that, as extensions to this question can overwhelm quickly, but yeah, JavaScript is a fine language for what you’re doing

All roads lead to woodworking

I think this belongs here.

I also love the idea of some sort of CI/CD pipeline with this in its linting stage