if you are fine with using the attached storage only for that single user, I’d suggest to mount it as /home/<youruser>
you can have an entry in /etc/fstab for that then and it should be reboot proof.
obviously you want to mount that storage elsewhere temporarily and move all data in there before mounting it at it’s final spot. and stop webserver/mariadb during the move to ensure data consistency…
also keep in mind the conf dirs have an immutable bit set, so you want to handle that accordingly 