@eaftos: having two NICs on a device may not provide the functionality you are looking for. A device will only use one default gateway, and thus one of the NICs for Internet connectivity.
If you use a 2nd NIC for layer 2 then that will be fine.
If your goal is to intermittently connect to a VPN from a device and have all traffic routed through pfSense, you’d have to find a way to route an internal source IP over the VPN and ensure an outbound NAT rule is in place as needed.