You mean the Tailscale part? If so, it is easy. Just install Tailscale on your VM and allow communication between the VM and your Proxmox Tailscale node with the ACL page on your Tailscale account. Make the Proxmox Tailscale node a subnet router or install Tailscale on the VM/Docker of each service.
Safest is probably Cloudflare Tunnels. Similar to something like Tailscale, but Cloudflare provides the Internet facing IP and all their protections. Problem is video streaming is against the TOS for Cloudflare free accounts. So that leaves out Plex type servers.
Next solution is to run a reverse proxy on a VPS and link the VPS to your home network via Tailscale. That away you don’t have to open any ports on your home connection.
Nice. Which tutorial did you follow? I’ve seen a few on the web.