Depends what your definition of "Hindu" or "Hinduism" is...
If you go far back enough, monotheism was and is still apparent within Hinduism. And Hinduism in itself is a foreign concept within South Asia.
Let me give you a brief history lesson.....I wrote most of the stuff in here already:
https://defence.pk/pdf/threads/implications-of-barli-inscription.661940/
Brief History Lesson:
Indus Valley Civilization, part of the earliest civilizations on planet Earth, I call them the
Big 7:
Depending on the book, article or the time period you look at, there can be anywhere from 6 to 8 major early civilizations. The
Big 3 are Egypt, Mesopotamia (modern day Iraq, parts of Levant & Iran) & the IVC based in Pakistan and Northern India. The Big 3 were also the first to form in our current understanding of known world history.
Indus Valley Civilization (3300 - 1300 BCE):
Broken down into 3 phases....Early Harappan Phase (3300 - 2600 BCE), Mature Harappan Phase (2600 - 1900 BCE), and Late Harappan Phase (1900 - 1300 BCE).
^Shows all 3 phases.
Then come the "Vedic Religions"....."religions" because that's what modern day Hinduism is...
Vedic Religions reigned in the Gangetic Plains while Buddhism was dominant in modern day Pakistan, evidence is such sites as Taxila, Ghandhara and the Buddha statues in Afghanistan.
Buddhism was suppressed throughout South Asia by the Hindus which is why it moved to China and South-East Asia.
Following the above timeline and the advent of Islam, people in the subcontinent started going back to monotheism. Yes, going back....which is why I said that monotheism existed within Hinduism (which is a fact you can look into) & has been there since time immemorial in many forms. Even our dear Chinese neighbors to the North had monotheism before they moved onto ancestor worshipping, and their religions.
^Indian source.
India: An Archaeological History: Palaeolithic Beginnings to Early Historic Foundations. Dilip K. Chakrabarty (2009).
Fun Fact: Aramaic was the precursor to Arabic. It was spoken by Prophet Isa/Essa R.A., known in Christianity & Islam.
You can see I brought in a comprehensive viewpoint....neither overly secular or religious. Since no matter how much people try to deny it, religion does play a big part. It did in the Ancient World and so it does in the present day.
Being overly secular or religious is where most problems start.