I've just been traveling in Germany - Dresden, Erfurt, Nuremberg, etc. Everywhere that I would have expected (with my US mindset) credit cards to be accepted, they were. Hotels - I didn't stay in any family run places. Restaurants. Shops. Transit kiosks.
Many times it was contactless. Often a signature was required. I never once had to enter my credit card PIN. (Of course I had to enter my ATM PIN.) In the past I did have to enter my credit card PIN at unmanned transit kiosks. But my new card is contactless and I used it in that way without a PIN to buy on-the-spot transit tickets. So easy!!
ETA: last day of my trip, in Frankfurt, I had to enter my credit card PIN (mine is 4 digits) to buy a transit ticket at a tram stop. I don't remember there being a contactless option.
In those places where I would have expected to have to use cash in the US, the same was true in Germany. Small vendor stands, for example. Tips. Tiny purchases, though I probably could have used the card for some of those, but would have felt silly.
I always kept coins for public toilets - €0.50 or €1.00.