How can I format my USB sticks using Linux so that they work on Android?

How can I format my USB sticks using Linux so that they work on Android?

So I have been stuck on this now for a few hours. Strange issues.

I am trying to format two usb sticks (one has a removable SD card, the other one is a SanDisk Cruzer) as vfat, which as far as I know is the preferred filesystem for Android USB OTG usb sticks.

However, now Android cannot see them or mount them anymore which means they won't show up in storage.

I think I was able to successfully format them as vfat on the RPi just now but they still won't show up on the phone.

I could reformat them directly on the Android phone but they won't even show up so I cannot reformat either.

Any advice?

Computer: RPi3B
Mobile phone: Samsung Galaxy S5

Vesa