Off course not satisfied I surged for a solution and have found it:
Not the Gboard app but the the ‘WiFiKeyboard’ app from FDroid did it! Alongside that one I have installed the ‘AnySoftKeyboard’ app as online keyboard and still the ‘Android-Tastatur (ASOP)’. At the settings under ‘Sprachen & Eingabe’ (= languages and input) I could set the ‘Physische Tastatur’ to ‘deutsch’ and now all the inputs, at online keyboard and at BT keyboard, are correct!
Edit:
Strange, WiFi and BT are different technologies, but I need a WiFi app to work with a BT keyboard.
You may be right! When I downloaded the open gapps I choose ‘pico’ and have got the file mentioned. Therefore I thought, it should have been the ‘pico’ version.
you can deavtivate the map in the start screen in the settings of the app… afterwards you don’t have any more problems…
Well I don’t miss or need any map in the app, so I deactivated it for me…
you can find it under: main-menu->settings (in the top)->Show map (Karte anzeigen)