Accidentally put grub on the wrong partition on the device, which it was not happy with. Was able to copy some files over, manually boot the OS, and reconfigure grub to be in the right partition, took me about 2 hours? Then I did it again on a different machine, and speedran it lol
Started with Raspbian when I first got my Pi, and have mostly used KUbuntu or Debian since.
Heads up, looks like this image was stolen, original source as best I can tell (based on the watermark in the corner, as well as being far older) is https://www.pixiv.net/artworks/67394923, by QYS3