Gilgit Baltistan and Kashmir was dominated by the Tibetan Bon Religion, Buddhism and folk religions (which still exist to this day).
KPK was dominated by Greco-Buddhism and Bactrian Zoroastrianism. There are some remains of Zoroastrian temples which were converted to Buddhist temples.
Northern Punjab was dominated by primarily folk religions and ancestor worship(which still maintains a footprint today); with some areas being influenced by Hinduism, Buddhism and Zoroastrianism. The people were hostile to the Hindu caste system.
South Punjab was dominated by primarily folk religions and ancestor worship with direct influence from Zoroastrianism. The largest city of South Punjab, Multan, had a massive sun temple dedicated to the Persian worship of Mithra.
Sindh was dominated by folk religions, nature worship (which still maintains a footprint) and Buddhism. Many tribes such as the Jatts were hostile to the Caste System and hence were persecuted by the Brahman Dynasty which took over after the murder of the Buddhist King.
Balochistan was most likely dominated by isolated and local religions influenced by Zoroastrianism.
You're over-exaggerating historic Hinduism in pre-Islamic Pakistan. Hinduism was not even an organized religion back, neither did anyone consider themselves to be Hindu or follow a Hindu religion.
We know from Vedic texts that people from modern-day Pakistan were definitely not Hindu. They ate meat, buried their dead and were hostile to the caste system - hence why they are always negatively portrayed in Vedic texts except when it came to their martial prowess.
Here are some quotes from their texts.
“who will save us from our mortal enemies in the Sapta Sindhu?”
“that (region) where these five rivers, emerging from the mountains flow, this Aratta (country) is called Balhika where the Arya should not stay even for two days”.
"I remember from the days of my youth that a slaughter-ground for kine and a space for storing intoxicating spirits always distinguish the entrances of the abodes of the (Vahika) kings. On some very secret mission I had to live among the Vahikas. In consequence of such residence the conduct of these people is well known to me. There is a town of the name of Sakala (modern day Sialkote), a river of the name of Apaga, and a clan of the Vahikas known by the name of the Jarttikas. The practices of these people are very censurable. They drink the liquor called Gauda, and eat fried barley with it. They also eat beef with garlic. They also eat cakes of flour mixed with meat, and boiled rice that is bought from others. Of righteous practices they have none. (8,44)"
