I skimmed this and assumed that formatting the SSD with
gnome-disks would be enough, when in fact it's necessary to first create a partition table, then format it, which can't be done from
gnome-disks as far as I can tell. I ended up with
/dev/nvme0n1 instead of
/dev/nvme0n1p1 which the other scripts assume to exist.
Side note: it seems strange to me that it's considered an advanced feature to run off the SSD instead of the SD card. Is that just because the job of partitioning the SSD is not obvious?