

as far as I know, there is no way to put a valid certificate like let’s encrypt for a service that is not accessible from the net
There definitely is. All of my local services run on a wildcard cert that I got from a DNS challenge with Let’s Encrypt. As long as the reverse proxy can access whatever source is issuing the certificate, and as long as the client browser can access public certificate ledgers and has DNS info about your services, things will work just fine locally.
I recommend Netbird to give access to services to your family members, for access control and for the DNS server it provides. It also gives you the bonus of accessing your services remotely.
Feel free to ask if you have any questions.




Huh? Why?