Can I play chaturanga on any of the main chess sites? Inspired by this question What rules are known for Chaturanga?
Chaturanga seems quite interesting, and some aspects of it, like no castling are being introduced in other variants: Kramnik's chess. Given that, say, lichess.org has so many variants, is there a reason why Chaturanga is not of them?
Possible reasons:

The rules are not exactly known.

Queen (Mantri) is much less powerful and pawns don't have a 2-square move option on the first move, which makes the game less interesting / drawish to many people.

Strategies were developed to draw fairly easily, (and that's why rule changes were introduced). This is a stronger version of 2), and probably not likely.
You answered your own question, with 1) and 2) being the main causes!
I don't know about 3), tbh, but it seems at least somewhat plausible (although stalemate was also a win in chaturanga so who knows!).
You say that it's not on main chess sites, but chess.com at least has it as a playable variant- can't speak for how easily you'll find a game there however.
It's also presumably not trivial to code the game, which is probably another reason why.