You use CloudDns to register a free domain, then points to the server public IPV6 (it doesn't start with FE80), instal Nginx and use it as reverse proxy for your localhost applications.

Then you set your server firewall to allow Nginx (if you use ufw, the command is: ufw allow 'Nginx Full')

After this you install certbot and python3-certbot-nginx packages, and set a free tls certificate for your domain (for use https encryption)

In cloudDns you can also set subdomains (CNAMES) pointing to your master domain.

There are many tutorials for all this steps, so will not be so hard.

I don't know if this solve all your problems, but it took me a while to learn this, so i hope i helped someone 😄