It's easier as in using already known tools. It's potentially less secure because sshd is vastly more complex, and allows literal (authorized) remote code execution, unlike fwknop.
You would absolutely not use openssh server for this. That's a terrible idea.
Pick a library. https://github.com/Eugeny/russh
You would absolutely not use openssh server for this. That's a terrible idea.
Pick a library. https://github.com/Eugeny/russh