Applying to Canadian Universities with A levels for CS

Hello! I'm an international student looking to study CS in UWaterloo, UBC, U of T (Saint George or Scarborough), and McGill, applying with A*AA predicted grades in math, physics, and CS, respectively. I also achieved AS grades of ABBC in math, physics, CS, and chemistry respectively, deciding to drop chem. My IGCSEs are mostly A*s and a few A's, with the exception of further math being a 4, and my extracurriculars are mostly math competitions, like certificates from the UKMT, participating in math competitions where schools select specific people in the year. I also undertook a physics EPQ, CS MOOCs with a verified certificate, and I made a website using Python, HTML and CSS.
I was wondering if I have a realistic chance of being accepted by any of the listed universities, given that competition is increasing each year. I was quite surprised by the McGill cut-off rate for CS and wondered if I should rely on what the website says. I would greatly appreciate an honest answer.
Also, I would like to know how much context matters in admissions. For example, the FPM course for IGCSE was not introduced at my school until over a year later, so no internal assessments were recorded on the transcript for that particular subject, nor was further math A-level offered. I also want to know if a school's reputation and location also matter for admissions. Would greatly appreciate the insight.