Are there any specific requirements in openwrt to get P2P working in netbird?
I have opened wireguard port that netbird uses, confirmed the port is open by testing with wireguard VPN to rule out any ISP issues and went as far as setting up STUN servers but nothing has worked.
netbird is installed in a proxmox LXC with the proper tun permissions.
Well that is one thing you normally do not have to do 
NetBird is very nice but if one of the routers you want to connect to has a public IPv4 and/or IPv6 address you can do it by using WireGuard but if not NetBird is an excellent tool you can use.
There is an OpenWRT wiki:
which currently lead to my notes I made while setting up.
If you have any questions feel free to ask
I’m not at the stage where I will self-host yet, just need P2P to work without self hosting first.
I’ve been using netbird and tailscale and thought these solutions would not need port forwarding but both do if you want direct P2P connections. Tailscale uses UPNP while netbird needs port 51820.
Do note I am not running netbird on openwrt, I only need to figure out why direct connections do not work.
I followed your guide, created new polices and groups etc but my connection is still showing relayed.
Yes that could well be related, using a container might need different settings.
But this is targeted at OpenWRT.
For Openwrt you do not need to open ports
I have als added instructions for setting up NetBird at my VPS see last paragraph maybe that helps
I followed your guide with new polices, groups, peers etc but still getting relayed connection.
I’m not interested in installing netbird on openwrt, so as far as i’m aware I do need to port forward but cannot figure out what I’m missing.
For my VPS I needed to open some ports, as described, but a VPS is not a container so cannot help you with that 