That's because Pakistan is an Islamic state. That's how it was conceived. That's how Pakistanis perceive themselves
India - is a more ideologically diverse country. Even among BJP supporters, you will find 4-5 definitions of what Hindu nationalism means
Because nobody really opposes the idea of Islamic nationalism in Pakistan
It is taken as a given
There is a great deal of debate on our constitution, on what the public culture of the land should be, on the nature of Hinduism, on the rights of minorities, among other things..
But that's the bare minimum line within the party
On how far the "state" ought to regard itself as Hindu - there is a LOT of diversity within the BJP - RSS ecosystem