I think I understand. You want your variable IP address to act as a fixed ipaddress so your variable address is always updated to the same fixed ipaddress and this is done by the VPN provider as well as encrypting the data. But you still need to setup port forwarding on your router as your vpn provider wouldn`t be able to do it , I think for you.
Years ago there was a little free programme you installed on your computer and as your computer booted up it updated your fixed virtual ipaddress. This was free so you could share different things without giving out your real ipaddress.
The router I mentioned the Asus Tuf gaming AX5400 from memory will let you setup 4 different countries for your vpn service you just setup the ipaddress of which box you want to send wherever using Openvpn or 2 countries with wireguard. I think from memory you can do port forwarding as its I thought a basic requirement for gaming. I hope this has helped a bit. The Asus site had lots f info a couple of years ago.