Could you please advice; what would be a very userfriendly and safe Android app to be used by the less tech savvy
to buy some BTC and keep them in their own wallet on their phone?
Friends and family like to buy a bit of BTC too, but exchanges and alike are way too complicated for them.
They just want to click & buy, have secure local storage and be able to sell, no trading functionalities required.
Does anyone know if these kind of "Mobile BTC Wallet for Dummies" exist or have recommendations?
No sorry. Your friends and family should be able to use Coinbase without any major problems. That one is as user friendly as it gets. Gemini is an alternative if you don't like Coinbase. If you start to accumulate bitcoin and learn your way around you would eventually want a hardware wallet.