Rivnuts from Homsstead on 4/16/2019 6:08:40 PM:
There is a Dick's Sporting Goods store in Homestead, PA about 9 miles from downtown Pittsburgh that opens at 9:00 am. There is a Lowes in that same shopping complex that opens earlier but I don't that they carry the camping-type gas canisters.
You already mentioned the REI about 3 miles from downtown.
If you really want a daybreak start, I could bring you one or more as I live near the trail and am up early in the morning.