> What about Prakrit and Punjabi?

There is no official "Prakrit", by definition of the term itself. "Prakrit" just means "natural" and the way I understand it, was the term for all colloquial dialects/languages across India.

"Sanskrit", on the other hand, meant "cultured" and its grammar, at least for the last 2500 years, is strictly defined by Panini (https://en.wikipedia.org/wiki/A%E1%B9%A3%E1%B9%AD%C4%81dhy%C...)