“I’m also considering U of Waterloo or U of Toronto”
Canadian schools largely admit based on stats. They do not care at all about grade 9 (your freshman year of high school). As long as you did not flunk out, they will completely disregard grade 9. You have all A’s since then.
Computer science is a very competitive major at both Waterloo and Toronto. However, I still think that you chances are very good.
Canada is also relatively accommodating to international students who graduate from Canadian universities and then want to stay on in Canada on a work visa. This is assuming that the economy recovers by the time that you graduate, but you have four years and the pandemic will have long ended by then.