I no longer have a VPN block defined in my nginx config on that GitHub repository. I rebuilt my lab on Proxmox a few weeks ago and haven't gotten around to implementing the VPN server again. If you look at the older commits on that repo you should be able to find an entry for it though. For example:
https://github.com/zimmertr/NGINX-Reverse-Proxy-Config/blob/849bb53ea7835cb5637764b5daf2ba8b352ccb33/tjzimmerman.com.conf#L158
https://github.com/zimmertr/NGINX-Reverse-Proxy-Config/blob/849bb53ea7835cb5637764b5daf2ba8b352ccb33/tjzimmerman.com.conf#L158