@Firewaller1
You do not need to worry about the WAN IP address assignment. It can be DHCP or static. It does not matter. pfSense itself should select WAN as its default gateway. Your concern is only the LAN side and you already have a static IP address for that.
I understand that you have a local network where routing is handled by a L3 switch and you have created a routed link between the L3 switch and pfSense. BTW, that’s my choice, too. In a case like that, pfSense does not know anything about your local network. Because of this, you need a gateway to your LAN on pfSense and one or more static routes. Also, pfSense needs to be the default gateway for your local network.
In your /30 link, you have two IP addresses, one on L3 switch and one on pfSense.
You need to use the pfSense IP address in the default route on the switch.
On the other hand, the switch IP address needs to be defined as a gateway on the LAN side of pfSense. This gateway needs to be used in the static routes to your local network. You need one static route for each LAN subnets you want to interface with pfSense. If the local network is in a completely different address space than pfSense, you probably could use a single, more generic, static route.
Placing a switch on the WAN side of pfSense is another issue.