The number of sunflower varieties out there is dizzying, including many branched ones. One thing I found challenging when searching varieties last year, is that not all sources will specify if the cultivar is 'pollen-free' or OP. There are many many male sterile varieties since that is used extensively in breeding, and for florists the lack of pollen is a plus. IDK how difficult it is to get rid of that trait. Anyway you can find branched OP's at places like Baker Creek, iirc they have quite a few.