First of all, let me clarify what I meant by burger availability. There are restaurants that serve burger in my city. But they aren't within walking distance convenient for takeaway. So I'd need to have a full sit down experience. There is also no delivery service except for McDonald's.
The last city I lived in had a great burger delivery service and I know others have, too. But for me the choice is between pizza delivery and takeaway from vietnamese, turkish, syrian or japanese restaurant in my street.
Something like a bbq restaurant is largely unheard of in Germany. Surely there are some, but it is super niche and probably not what you would consider bbq. Delivery service for these places is even more rare.