Hello Dapsley!
I made a similar post 4 days ago that concerned adding the Mysorean Rocket to the game. But Instead of making it into a Mercenary unit I was suggesting that it could be a new unique military unit to [India] that would be trained from the [Castle] and the [Agra Fort]. https://forums.ageofempires.com/t/1-new-trainable-unit-for-the-aztecs-haudenosaunee-incas-and-the-indians/207800
The reason for making this unit exclusive to India was so that they could have access to an alternative long-range siege that didn’t take up as much population space as the [Siege Elephant].