Okay, Nisarg is definitely using sign language. I’d thought so earlier.
Since then, he’s signed “milk” a couple of times more. I’d been trying to get a video, but he does it rather absently, and when I approach with my phone in hand, he starts interacting with me, waving and sucking his fist. Finally, I was able to capture the tail end of it as he got hungry when my mother-in-law was holding him….. Its not very clear, he does it just once, but check out his right hand. He was doing it with both when I came close and stopped 🙁