patlaw The question is whether I can backup my desk phone and restore that backup to a second OBI1022 and have GV work on the second phone.
No, but you could install modified firmware on the second device, restore the backup then manually enter the missing GV parameters to create a clone.
You might use such a clone as a “cold spare”; if the first phone failed you would power it down and connect the spare in its place. It might also be useful, e.g., in a vacation home, where you would power off the phone in your main home and power on the one in your secondary residence.
However, if your intent is for both phones to function at the same time, a clone is not what you want. GV does not support multiple registrations on the same account(s); neither does VoIP.ms on the same sub-account. For this, you could configure the original “master” phone to fork incoming calls and relay them to the “slave”. Outgoing calls from the slave would be sent to the master, which would relay them to the GV or VoIP.ms accounts. This is a fairly complex configuration, but does not require special firmware in either device.