I wonder about reincarnation in the Avatar universe beyond the Avatar - since effectively we assume that anyone who doesn’t transcend and become pure spirit (like Yue and Iroh did) reincarnates, but the Avatar is special because there’s the ability to know who’s the reincarnation (since that person is the Avatar), and there was the access to past lives the continuity of Raava provided (and will provide again for Korra’s future reincarnations). But everyone else reincarnates too.
It was a truth in the original series bible that never came up on screen, that Momo was the reincarnation of Monk Gyatso. I assume he spent the 100 years reincarnating into various animals at the Southern Temple to wait for Aang. My headcanon is that that soul, deeply tied to the element of Air, is now Jinora in Korra’s time.
A thought occurred to me on Azula, if she isn’t still alive somewhere in Korra’s time. What if what her soul needed above all else was a second chance? Not peace, not punishment, but a second chance to not go down the path she went down in her life as Azula. And so she was reincarnated into someone dotted on by a father who would craft her into his weapon, just like before, but when her father’s darkness revealed itself, this time she could choose “No” and not follow him into the infliction of suffering on others - and that’s just what Asami did.