However, the base partition size of the root file system is merely 7GB, and I’d like to increase it to fill the entire SD card. I’ve tried using gparted, but have failed to get it to boot after any change.
The tools complain about two things:
GPT needs to be resized to fit the device
The backup table is not at the end
Letting gparted fix either of these makes the SD card unbootable, even if I don’t change any of the partitions themselves. I’m at a bit of a loss on what to do, and reflashing to try again takes quite a while. Any help would be appreciated!
gparted does pretty much the same as what you listed there. Just to be sure I now did the same thing with parted, answering Fix for both questions, and it is now unbootable again.