Aaaanyway, so tech.... On the building-a-new-Linux-workstation front, I came regretfully to the conclusion that
btrfs-convert isn't ready, especially not in the versions available on Linux Mint, and so, wanting to move on with my life, I did a bitwise copy of my Laptop's ext4 partition to the new SSD, resized it, and called it a day.
Whenever a stable distro has a
btrfs-progs version not preceded by a string of concerning fixes to
btrfs-convert, and a more recent kernel than 5.15, I'll install it and convert the partition to BTRFS. Until then... I'll wish I had it. Cost-free snapshots are addictive; you can't go back.
Otherwise, work on Umpire is coming along; also put a few cycles into running GPT-J on the new GPU - a work in progress.
Unrelated: album recommendations welcome. All genres.