VPN and open ports

I have a NAS where I have a Plex server and also a safeguard VPN configured. To access my plex from outside I need to forward/open a port in my router, I know this imply some degree of risk. Checking in internet I read I should use a VPN to avoid the risks. Here is my question, yes I know connecting to my Plex from outside using the VPN client in my phone will encrypt the data so nobody can understand what I am sending or receiving, but as far as I understand it this has nothing to do with the open port in the router needed to make my plex server to work, using VPN will not avoid the need to open a port in my router and also will not decrease in any form the risk of an open port. Am I misunderstanding something?