One thing that always bothers me when the Abrahamic religions try to present evidence of their God, is that the evidence, even if the claimed experiences are fully believed, can always be explained by supernatural phenomena they believe in that is not God. For example, demons/djinn can explain literally everything experienced they claim is for God, without God. Thus adding a supreme God to the mix is completely redundant. Usually, apologists will make a completely baseless assertion that supernatural entities prove God, without reason or attempt to disprove religions that believe in the same entities without a supreme God.
Now while the supreme God is important for worship in Hinduism, whether or not he exists has almost no impact on any of the other beliefs like reincarnation, so I don't really mind as much when Hindus claim evidence for God, because it doesn't change much if it turns out to be the other stuff.
Still, the question is worth asking. What is the proof for specifically the supreme God?