All pharmaceutical sold in Canada are approved through Health Canada and will have a DIN identifier on them if they’re legitimate. (https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/fact-sheets/drug-identification-number.html)
Canadian generic drugs are overwhelmingly made in Canada by one of the many generics companies in Quebec/Ontario. Wherever Canadian-sold drugs come from, be it India or any other country, it is not because of some “Commonwealth” relationship. The “Commonwealth” designator is just a sort of old-boys club of being able to claim the Queen/King as head of state, and has no other real meaning - it’s not a trade alliance and where there are treaty relationships, it’s probably a result of history. Health Canada approves all pharmaceuticals and regulates labelling - just because they come from a Commonwealth country doesn’t mean they get a free pass.