Canadian FG is talking about Canadian zone 6, which is different from the USDA zones we are used to talking about. They have their own zone system. On the USDA system CFG is probably in zone 3 or possibly 2.
" Today, the USDA map, which was last updated and released in 1990 (based on weather records from 1974-1986), is generally considered the standard measure of plant hardiness throughout much of the United States. Hence we have the USDA Plant Hardiness Zones.
A similar map for Canada has been issued by the Canadian government's agriculture department." https://www.backyardgardener.com/zone/index.html#usda The article has links that show the US system and the Canadian one.
But yes, even in zone 2, I would think you could direct sow your chard. It is quick growing. The limiting factor for you growing annuals like chard is not how cold it gets in winter (which is what the zone system measures), but the length of your frost free season. It looks like your average last frost date in spring is around May 15 and the average first frost date in fall is around Sept 1. So anything that can't grow to maturity in that time needs a head start indoors. But swiss chard is really good for that climate. You can plant the seed outdoors, direct seeding, as soon as the ground can be worked, even though you will still have some freezes after that and it will survive the first few fall frosts.
What you would need to start indoors would be things like acorn squash, which have a pretty long growing season, can't be planted out until the soil is warmed up, which is later than the last frost date, and will die at the first touch of fall frost...
So anyway, like everyone has said, yes indeed, direct seed your chard outdoors. Incidentally, I grow the bright lights too and I love it! It is the most productive thing in my garden growing and growing all season long.