Heh, yes I suppose I could have checked what was the conflicting package but just as you noted, no packet mangement tools in rescue mode.

It is possible to use the toolset of the device rootfs on mmcblk0p28:@root but that is a bit tedious and factory reset also nicely zeroes the btrfs state.

BTW it seems that the "no cellular connectivity after boot" is a real recurring problem; it manifests on about 20% of reboots.