Thank you for the Hint! Unfortunately, the app didn't show any device, but it was the same with my Xbox-controller. From what I found, it seems I might need to finally root my android device...
same here, my Betafpv LiteRadio 2 SE is not detected on a recent android 10 phone (nokia 6.2) with OTG cable who work with all other device (usb key, keybord, ...)