Any USB stick with FAT32 or exFAT formatting can be used.
However, the following USB sticks are recommended for the best performance on the systems:

SAMSUNG: USB 3.1 Flash Drive BAR Plus (MUF-64E3/EU)
https://www.samsung.com/de/memory-storage/usb-flash-drive/usb-3-1-flash-drive-bar-plus-64gb-silver-muf-64be3-eu/

SAMSUNG: USB Flash Drive FIT Plus (MUF-64AB/APC)
https://www.samsung.com/de/memory-storage/usb-flash-drive/usb-flash-drive-fit-plus-64gb-black-muf-64ab-apc/