Not that we have live recordings of.

But there is no doubt that he was a pioneer of music theory.

https://en.wikipedia.org/wiki/Pythagorean_tuning

https://www.jstor.org/stable/24045969 (Pythagoras and the Origin of Music Theory)

https://arxiv.org/pdf/2104.00998.pdf (Dynamical systems, celestial mechanics, and music: Pythagoras revisited)

We don't know. From what I've read, we know a little bit about early theory, but don't know precisely what scales and intervals they were talking about.

We know quite a lot about Greek music theory (Thomas Mathiesen's Apollo's Lyre: Greek Music and Music Theory in Antiquity in the Middle Ages is the go-to source here: https://archive.org/details/mathiesen-1999-apollos-lyre/page...). Of course we don't have recordings, but we do have a solid understanding of the theory, and some very good guesses as to the scales and intervals.