@CVB2000 I don't really know much about AMPRnet, but for normal internet https, couldn't you just get certs for instance with Let's Encrypt (nowadays handling cert has become very easy with certbot or alike)?
If you need to have also the http URL for AMPRnet (I don't really know how this works), you can still have both (simply our website will only redirect to the https, but you can use the other one in other systems if needed).