Many thanks for the good and quick answers - I am always delighted with the fast and helpful support here in the forum!
other8026
I immediately tried out your suggested solution, installed the Cryptomator APK and tried using an "USB-stick-only" vault - it works perfectly, for transfering files between computer and my GOS device - thanks for the hint!
The only thing that doesn't seem to work (at least I haven't found a way yet) is copying entire folders on Android into the vault (on the computer this works fine).
MarsTrue
Thanks for your tips, those would also have been very helpful solutions if I wasn't already using Cryptomator on the computer.
Too bad EDS lite doesn't seem to be updated anymore - without being an expert, I share Dumdum concerns.
The hint of using USB sticks with a build-in keypad is also quite smart, especially because you could use such a stick on your computer, phone and even connect it to the tv.