Xfer course backups to folder outside of moodledata and put them in category named subfolders ... social studies courses (cat 3 in old site) to an 'ss' folder on destination server.
Install moosh on new server ... once installed, moosh has a command to restore a given .mbz file (a mdl backup) to a category ... category has to exist.
https://moosh-online.com/commands/
clip from above that applies:
course-restore
Restore course from path/to/backup.mbz to category or existig course.
Example 1: Restore backup.mbz into category with id=1
moosh course-restore backup.mbz 1
Example 2: Restore backup.mbz into existing course with id=3
moosh course-restore -e backup.mbz 3
Example 3: Ignore pre-check warnings, like restoring backup from higher Moodle version.
moosh course-restore --ignore-warnings backup.mbz 1
Example 4: Restore backup.mbz into existing course with id=3, overwrite course content.
moosh course-restore --overwrite backup.mbz 3
'SoS', Ken