Yes it is possible to implement https and compression and even http/2, but I don't believe that in the near future it will be available in the Nim, moreover http/2 is a complex protocol to implement. So whatever Nim web framework we use, we always need Nginx or Apache.
But even http/2 will be replaced by [http/3](https://en.wikipedia.org/wiki/HTTP/3) soon. I believe that FastCGI is more scalable and should work in the future with any http protocol due to php.