How us this related to Hindu mythology?
It's not but I am just saying that I grew up learning about it and I always wanted a gay lovestory with a shapeshifting snake. My dreams are coming true with this.
You should try reading "Summoning a BL Fan to Another World"
Does it have supernatural-esque setting?
There are a lot others.
Yes
I was raised Hindu and whenever I watched anything related to shapeshifting serpents, I was always like "I want queer representation in Hindu mythology!" AND NOW I AM GETTING IT!! It's omegaverse with shapeshifting snakes. GOD BLESS!! All these years of consuming Naagin franchise has come in handy.