Maple syrup is a classic Canadian gift, but it's heavy and glass bottles are risky to carry around. Better to get maple candy, IMHO.
Coffee Crisp and Oh Henry bars are not vegan, but classic Canadian chocolate bars.
I like to buy clothes when I travel, so I remember my trip whenever I put them on. I have good luck finding things in Winner's and Marshall's; if you want a Canada-only brand, take a look at Joe Fresh.
The usual tourist tat: keyrings, mugs, shot glasses, etc. Anything with a maple leaf on it.
Dollarama has lots of branches and often has Canada-branded items, especially in the run-up to Canada Day. It's a good place to get keyrings, stickers, pencils, etc.
No Frills is a supermarket with strong branding in their "No Name" line. It's a popular riff for joke products; they sell a few of their own.
Chinatown has lots of souvenir outlets at reasonable prices.
SoMA Chocolatier has a few branches (King & Spadina, the Distillery District, Parkdale). They're a high-quality chocolatier; expensive, but not eye-watering. Good chocolate is a nice gift already, but some bars have Canadian ingredients like ice wine sloes and Newfoundland salt. They used to sell a bar with a map of Toronto on it too.
Spacing has a store at Richmond & Spadina. They sell a lot of Toronto-branded goods; expect streetcars, TTC logos, neighbourhood badges, raccoons, etc.
Second Cup is a popular Canadian coffee chain; they often have nice mugs.
Blue Banana in Kensington Market has a wide range of unusual items.
Toronto Public Library sells reasonably-priced tote bags.
Hudson's Bay is an iconic Canadian department store, especially known for its stripes. There's a shop immediately south of the Eaton Centre.
Pretty much all the provincial parks have a park store that sells merchandise; a T shirt or hoodie is a good gift. They'll give you a nice reusable bag if you spend about $25.