There are some investment "bridges", usually ran by Canadians who made money in the States and are now helping out. I'm not well versed enough in the legality of US-entities investing in Canada, but in principle yes, the opportunity is there.

In Waterloo I think it's possible with a seed fund that puts in 100-150k at 2 to 3M valuations before the good ones get picked up by YC.

A lot of Canadians move down to the states anyway because developer salaries are like 2-3x higher.