itch.io

Is there a reason, why this game is blocked for Germany on Steam? The screenshots indicate nothing. Strong language and a big chest are no reasons.

Yes, but as a creator you can create as many steam keys as you like and supply to your old itch.io customers, others did it before and still do it now. You just have to decide your pricing and end your "Name your own price" model, to comply with steams competition rules.