As for credit cards, that's pretty common, traditional banks want to see your salary landing on your checking account for a few months before they issue you a credit card. Comdirect gave me a prepaid VISA in the meantime.

Anyway I ended up using a debit card (the MasterCard from N26) for almost everything, and later on I got a Gold credit card from Advanzia (I believe they do get information from the Schufa, but you also start with a pretty low monthly limit and need to prove them you pay your bills before they raise it).