This issue is resolved.
I opened a support ticket, and they had me reimage the device with the 21.02_1 image (they linked me the correct image to use). There was an option to recover an existing config before install, and using that I was able to recover my old config.
System is back up now and working ok, original config intact, so it was an easy recovery.
I have also learned about the free online config backup service PFsence provides. I will be using that from now on, incase this happens again.
Thank you.