I am not Canadian. Apparently our ages make a difference. I remember as a youngster my mother singing to my siblings when they were infants:
"Bye, baby Bunting,
Daddy's gone a-hunting,
Gone to get a rabbit skin
To wrap the baby Bunting in."
Babygrow was my first thought, and that of my wife, however, babygrows are only really suitable for inside wear - the picture looks as if it is designed to withstand a Siberian winter. The pram suits are the substantial ones.
This article suggests they are commonly used to keep babies warm during car rides. I imagine that's a bigger problem in Canada (and the northern U.S.) than where I live.
Since baby bunting bags are sold at major retailers, they're mainstream and often thought of as safe for your baby. But before you tuck your baby into a seemingly safe bag, consider the possible dangers. In fact, the Canadian Paediatric Society specifically warns against using baby bunting bags at all, opting for a safer alternative keeps your baby warmer and lowers risk of suffocation.
I’d never heard bunting as the name of a baby suit in the UK either. Maybe the name was purloined from the children’s rhyme “Cry Baby Bunting”?
The Babygro — a white terry towelling all-in-one baby suit (no hood) — was standard newborns’ attire from the early 1960s (End of an era as Babygro closes Kirkcaldy factory). It looks like the name, albeit often spelt babygrow now, still gets used even if the brand is no more. Oxford and Cambridge both have dictionary entries for it.