Travelers (and locals) cannot buy Cannabis products containing THC in Germany, and this may not change. You can't lawfully take weed from the German neighborhood who continues to be growing it for their personal use in your house. This might criminalize you and him. I.e., your Airbnb host is https://ericklgvkx.wikicorrespondence.com/5179824/buy_cannabis_in_germany_fundamentals_explained