Since the beginning, we delegated the TLS encryption support to a reverse proxy server, mainly Nginx. Under Windows, you could setup the http.sys HTTPS layer as usual, as a native - even a bit complicated - solution.
Nginx has several advantages, the first being a proven and efficient technology, with plenty of documentation and configuration tips. It interfaces nicely with Let's Encrypt, and is very good for any regular website, using static content and PHP. This very blog and the Synopse web site is hosted via Ngnix on a small Linux server.
But in mORMot 2, we introduced a new set of asynchronous web server classes. So stability and performance are not a problem any more. Some benchmarks even consider this server to be faster than nginx (the stability issue mentioned in this post has been fixed in-between).
We just introduced TLS support of our socket-based servers, both the blocking and asynchronous classes. It would use OpenSSL if available, or the SChannel API layer of Windows. Serving HTTPS or WSS with a self-signed certificate is just a matter of a single parameter now, and performance seems pretty good, especially with OpenSSL.