The charging cradle is connected via Micro Usb, which is why it did not work for me. However, the UsbC port is free and can be used for OTG while the tablet is charged in the cradle via a separate cable. But: Charging cradle only fits without case.

HalloDooMiix
I have just tried it out. I am thrilled. Keyboard and mouse are recognised.
Loading from other devices works. Thanks for the tip/question