After some serious heartbreak and feeling things weren’t going to end well for me I found Haioken’s Post
I couldn’t for the life of me mount the partitions in any useable way, so I went the recovery route. His command suggestion was the command:
btrfs restore /dev/<btrfs-device> <mounted-location-larger-than-btrfs-fs>
Luckily my NAS is quite small, only <2TB, so I had a spare drive that could be used for recovery.
I mounted another 2TB drive, and ran the command but with a slight adjustment:
btrfs restore -iv /dev/<btrfs-device> <mounted-location-larger-than-btrfs-fs>
Setting the -i for ignore errors, and -v for verbose, allowed it to get passed some errors it was having restoring content from docker container paths in the RockOns share. I’m not sure what, but that was forcing the restore to stop. And setting it to -v, verbose to let me watch its progress in realtime. I’ll recover my data, and likely rebuild the drives and shares again.
Thanks Haioken-from-the-past for helping me out in a pinch!