“This blood-dependency is in contradiction to the Gandhabba idea, I think.
I think it is due to commentary?”
Gandhabba (at the moment of patisandhi) is just a few suddhatthaka. How can it have blood?
It is hard to even imagine how “small” a suddhatthaka is.
– The smallest micro-organism can be seen with a microscope.
– Such a micro-organism would have uncountable billions of suddhatthaka.
– A suddhatthaka can be seen only by a Buddha.
So, definitely, there is no blood in a gandhabba!