You used the standard XAMPP, not XAMPP lite, right? So presumbaly, Apache and MySQL are not running as services, and you start them with the Control Panel?
Move the XAMPP folder to the root of your USB drive.
run setup_xampp.bat - it will relocate XAMPP (and check everything).
You need a host machine that is running Windows, no matter what to run XAMPP for windows
Boot a Windows Host, plug in USB drive
go to XAMPP folder on USB drive -
start the XAMPP Control Panel
Start Apache and MySQL if needed.
should work - I just tested mine
Be aware that if you have scripts with dependencies, or you have switched to hostname TCP/IP sockets in MySQL you may need fixes.
Good luck and Happy Holidays