"If everything real is made of physics, you still must either explain how certain patterns of neuronal excitations are actually green, or you must assert that nothing is actually green at any level of reality."

This is a 'why' question, not a 'how' question, and though some 'why' questions may not be amenable to deeper explanations, 'how' questions are always solvable by science. Explaining how neuronal patterns generate systems with subjective experiences of green is a straightforward, though complex, scientific problem. One day we may understand this so well that we could engineer quales on demand, or create new types of never before seen quales according to some transformation rules. However, explaining 'why' such arrangements of matter should possess such interiority or subjectivity is, I think at least based on everything we currently know, unanswerable.