If it’s meat, looks like Rocky Mountain Oysters. Thought of this fine community the instant I saw it. Your guess is as good as mine. OP stated, ‘Good God !!! Please don’t tell me they’re some animal’s kidneys - that’s going too far , pizza explorers…… baaarf!!!’.
Please remove from internet.
This is how I imagine pizza would look like in a city run by Tolkien Orcs.
That’s like if Timon and Pumbaa managed to make a pizza.
Grubwurst.
Don’t worry about them being kidneys, they look more like rocky mountain oysters to me