Beyond that, Taj Mahal was created by a Muslim ruler of one of many empires/countries that eventually make up British India. So on that note, we can say that Taj Mahal is more Pakistani than Indian.
No, you cannot. Anything muslim is not the property of pakistan. India has some 170 million muslims, and so the second or third largest muslim population in the world. Whether it was commisioned by a muslim or not is not a criterion to be considered Indian. Muslim does not mean non Indian.