I’ve visited the burbs of Pittsburgh at least 30 times, mostly for weddings and funerals over the past 30 years.
I tend to get more home cooking than restaurant food when I visit.
These are some regional things that I’ve had a lot when I’ve visited.
The donuts. Pittsburgh still has good old school donuts, that don’t cost $4 each, something that Toronto no longer has. Mac’s donuts (not convenient to downtown, not suggesting the drive, but if you happen to be nearby) is the place my uncle always bought his donuts.
Prantl’s burnt almond torte. I know rstuart doesn’t enjoy nuts, this is more for Christina.
Prantl’s does sell nut-free stuff. My cousin, who had a side gig selling wedding cookies for cookie tables, loves this torte. I sent one through Goldbelly to my uncle in Colorado for his bday 3 years ago. They’re available for shipping.
Primanti’s sandwiches. It’s a chain. There is at least one location right downtown. I don’t know which is the best one to order. Fries are added to the sandwich. Fries are also added to their salads.
I enjoyed one New American meal downtown, the week of a family wedding. I’ll check to see if that restaurant is still in business.
Other things Pittsburgh does well: Italian American food that is distinct from what’s available in Toronto. Perogies, sausage, kraut, again, Americanized versions which are distinct from what’s available in Toronto.
The regional sandwiches are distinct from what we have in Toronto.
The The Dor Stop Restaurant (breakfast) . I still haven’t been but it’s been on my radar for 20 years.
In terms of Pittsburgh regional foods I haven’t seen in Toronto: Strawberry pretzel salad 
I love it. 
I didn’t try this until a family reunion in 2018. It’s potluck food.
City Chicken ( it’s actually usually pork, sometimes veal)
If I had more time, I would want to spend more time poking around Squirrel Hill.
