Great thread Rainer! 
I agree with Viacheslav that looking in areas that already interest you could be a great place to start, or, if you’re open to anything, what about one of the #erlang-frameworks-iot?
@mworrell seems pretty active in the Zotonic thread which makes me think he’d be very open to help - who knows, maybe you end up loving the project so much you end up being on the core team 