So, I was thinking about the evolution of instruments in Indian classical (Hindustani, to be precise). We know Sa and Pa are achala swaras, and don't have any tivra or komal forms. Sa and Pa form the structure of musical system itself, hence they are held invariant. But, has this had any influence on the different instruments used during performance? For instance, the Tanpura as a drone generates Sa and Pa as reference (please correct me if I am wrong). Has this "invariance" of the two notes caused any changes in the way the instruments were fabricated over time, and the way they were played?
I know, the question sounds vague, so please do comment if clarifications are needed. And I am a beginner with a bit of idea on Classical music, so please excuse me for trivial mistakes.