@stephenw10 had a backup machine I upgraded... tested and then upgraded active system.
Still have a question on if backup config file should be in root of FAT32 partition or in E:\config\ -> I had it in both.
Process I followed was to:
change interface to em0 pre-upgrade and disable the shellcmd script.
Take backup and upload to usb key
Connect my Bell MTS ONT to pfSense
Reboot and install new
This found the config, recognized and got internet DHCP address for WAN on em0 and installed packages as there was an active internet connection.
No other config changes were needed.
This has been quite a journey from when I first started this thread! Glad to see my script is no longer needed.