I do see the way via FDF thanks for that. It's unclear why I couldn't find it on search engines. Is Air Caraïbes not on those?

I think my point is different: I get it that any one single airline would fly maybe once a week but the US and Canada together have 10 plus airlines so surely that would give you at least one option a day. Even between Air Canada and Air France, the schedules could be in a way you get daily service. Now of course these are lines have no incentive to provide such spread in schedule. I'm just bemused.