My transition from #nginxProxyManager to #caddy is complete. I created 2 LXC Caddy instances: one for public services (with #UFW) and another for my private ones. This setup limits exposure to potential unwanted visitors.
Now, my #Proxmox cluster is available with load balancing for both IPv4 & IPv6.
Globally, the transition is easy. I only have some trouble blocking the outside traffic on Headscale Admin, with the reverse proxy of Pi-hole Admi/API, and of course, IPv6.