Tracking someone who was last seen in a homeless shelter in Ontario 1974 but died in 1999

Hey very knowledgeable people! I finally received my Ontario (Canada) death records search on my grandfather, who was last seen in 1974, and it turns out his death was recorded and he spent 25 years in Toronto with zero records I can find of his work or whereabouts.

He became estranged from the family after becoming a violent alcoholic, had a proper divorce from my grandmother, and lived in a home that they owned until it was condemned for lack of heating. He turned up in Seaton House in 1974 and my father and his siblings assumed their father dead, having turned to the police to track him and finding nothing.

I didn't even expect to find a death record but it turns out it exists, and he died in 1999! Quite a shock to all of us. He spoke limited English (Polish), lived around the Trinity area in Toronto, and that is basically all we know.

I have ordered the fancy long form death certificate that can tell us where and how he died and who reported it but that is months away from coming back.

Are there any of you amongst the geniuses in this group who are great at tracking down people who lived probably in rooming houses and shelters?

Any help or advice would be greatly appreciated! Thank you so much!