A government may introduce a list of identifiers of devices allowed to operate in their territory. With relatively frequent verification to prevent the use of captured devices.

Not a bad idea, but I doubt they know how many they have or their citizens have. Let alone serial numbers

IIUC the critical use is by military units, so a process to list all the serial numbers shall be quite straightforward

That’s very clearly a problem. But that wasn’t the one Musk weighed in on, he just blocked Ukraine at some points in time.