Orange pilling in Germany is so hard. People instantly tell about the tax authorities and how they don't want to even think about the hassle for those bare exception of a client.
Discussion
You need to talk to those who know the value of cash. Small shops, farmers, restaurants and craftsmen. Also it helps to introduce them to Monero as well. Bitcoin to store value and Monero to accept digital cash with ease.
Forget about chains or big supermarkets. They are the result of the fiat economy and will be the last to adapt.
I asked the owner of a cafe who had a "no cards, cash only" sign. He said it wasn't worth it for the remaining season.
First step is under the table. Make him install an app or bring a cheap phone yourself preloaded with a good wallet e.g. Cake that you leave him for the season.
Step two: Come back with friends regularly to make him aware itvis worth to put some time into this.
Third step: Bring some mini server installed with BTCPayServer.
You encounter merchants not in one go. Every metchant is at least a one year project.