I have a Pi running PiVPN, which is now connected to a router running OpenWRT. Does anyone have a link for me where someone describes how I have to set up OpenWRT regarding port forwarding and Firewall-Settings for PiVPN/Wireguard?

I THINK I have the port forwarding figured out, but the firewall-settings confuse me. Do I even need to set up a traffic rule?

It was easy on my Fritzbox-Router, but I find OpenWRT to be a bit more complex with all the functions it offers.