Must the virtualmin panel really use a self-signed cert, or is there a way to add an actual certificate?

Hello,

Long story short, I noticed that letsencrypt or certbot will only work for virtual domains WITHIN virtualmin: accounts that have a domain name and are listed within virtualmin.

However, the virtualmin/webmin administration panel itself ( server ip:port number, virtualmin is not loaded from a domain but from my dedi's IP address), in my case, I don't see any other way that letting it rely on a self-signed certificate.

I'm filing it as a "just in case" request, as this is nowhere near a life or death situation: please, would someone know if there's a workaround this situation, and somehow, one can add a browser-valid (not generating a security warning) certificate to the virtualmin/webmin administration?

Thanks a lot if I missed the obvious and someone is kind enough to share the information with me :)