Note that in historical Byzantine musical culture, there are no absolute pitches at all. Their notational form is entirely intervals from some arbitrary root note.

Similarly, in Carnatic and Hindustani classical traditions, the note names (Sa, Re, Pa etc) do not denote pitches - Sa is always the root, whatever it is, and the rest have a somewhat well defined intervallic relationship to it.

I personally would not use "harmonic value" to describe this, since it occurs in music that (broadly speaking) lacks harmony. The key point, IMO, is that what matters are sets of intervals (ratios, if you prefer) rather than actual pitches (as frequencies).

^^ THIS

Hindustani (and Carnatic) music indeed do not denote pitches for a very sound (pun intended) reason: They let singers choose the root note (Sa), and thereupon the melody is built. Most (all?) of Hindustani music is melody-based, not harmonic based (like Western music). And the melodies are themselves created within the Raga framework. Raga is like a mode (but not exactly that), and is hard to explain within the constraints of Western music theory precisely because that concept does not exist in western music per se. Which is why most Indian classical theorists call a raga a "melodic framework", and leave it at that (or expound on it, as the case may be).

A great reference for Indian classical music is [1] and and more recent one [2]

[1] The Ragas of North Indian Music, N.A. Jairazbhoy, https://archive.org/details/dli.ministry.26725

[2] Rāgs Around the Clock, A Handbook for North Indian Classical Music, with Online Recordings in the Khayāl Style, https://www.openbookpublishers.com/books/10.11647/obp.0313#r...