In case you want a quick example of a backend application in Nim, I've written a small post[1] describing how to create a room based chat using it and HTMX. In total, it's around 70 lines of code (though it doesn't cover more advanced use cases, like username collision). I too have moved from Go to Nim, the syntax and ease in which I can turn a feature into code has been much better.

[1]: https://arhamjain.com/2021/11/22/nim-simple-chat.html