Is it obligatory to inform the government about a passport that entered illegally, and what is one's duty towards a father's grave after burying him in cemeteries known for grave desecration and selling the deceased?

We ask Allah to have mercy on your father. If there was any wrongdoing in his burial, then the sin is upon whoever undertook that. It is highly probable that his body has decomposed, so there is no benefit in pursuing this matter. You should busy yourself with supplicating for your father and honoring him after his death.