When I ran the same “Move Data Disk” on a Yellow to move from CM4 eMMC to a SSD, the original user partitions were still on the original eMMC disk:
Overall, unless you have *nix sysadmin skills 
, and have already tried removing the external USB disk and rebooting (i.e. the user partitions might still be there and usable without the external USB), I’d factory reset the ODROID-N2+ and restore from a recent backup.
If you have *nix admin skills, try booting a live distro, and try fdisk and fsck on the external USB to see what made it across with the transfer. The partitions might be mountable for recovery, but getting a full set of consistent data will be the challenge.
If you don’t have a recent backup, painful as it is, learn the lesson, and try mounting the external USB on a PC to get the main YAML config files. Recovering the full database from tainted media can be done, but again needs *nix admin skills.
An external USB stick is unlikely to survive the database writes of HASS so try a small SSD in a USB enclosure next time if the on-board eMMC is a problem. Note that loading up /media used to be a good way of making HASS backups very slow and unreliable - which is why the new ability in 2023.6 to mount external NAS storage is a better option. The media is available, but not part of HASS backups.
If this helps, 
this post!