There wasn't any persecution of Hindus during the Sikh Empire since Sikhs and Hindus at the time were MUCH closer to each other in their practices and traditions and than they are today, and there was next to 0 religious frictions between members of the Sikh and Hindu Dharma.

However the khalistanis of the modern day have a clear disdain for Hindus, and view the Hindu establishment as their number #1 enemy, most likely Hindus would be persecuted by khalistan government if it became a thing.

Hindus are 40% of Punjab, and have been there for thousands of years before sikhi came into existence. It's for the best that the Hindus care for their own people and not let the fate of the Punjabi Hindus go into the hands of khalistani radicals.