How complicated is your pfsense setup? If it's simple - minimal rules, minimal static DHCP leases, schedules, aliases, etc., if it were me, I would just type everything in from scratch.
How experienced with pfsense are you? If you want to a straight swap, you need to export your settings from the SG-2440, edit them in a text editor to match the layout of the SG-3100, then import into the new pfsense box. If you do that carefully, it should work just fine.
Keep in mind, the innards of the SG-3100 are different than those of the SG-2440. There's a switch hiding in the 3100 that needs to be accounted for. It's not impossible, but I've read over and over about users that are new to that layout getting stumped on upgrading.
Here's the guide on the switch ports:
https://docs.netgate.com/pfsense/en/latest/solutions/sg-3100/switch-overview.html
Hope that helps.
Jeff