You can work more than 20hrs with on-campus jobs. Salary depends on position, but usually around minimum. With literally no “Canadian work experience”, international students mostly get accepted to entry level posts. I wouldn’t count on these jobs to pay for tuition, rather just a supplement fund for your cost of living (additional funds for your rent or groceries, etc). For domestic students maybe, but fo internationals no.
I worked both for the college (peer tutor) and a private contractor (fast food attendant at Tim Hortons). By personal choice, I limit my hours to a max of 20 despite legally being allowed to work for more than 20. Juggling between work and study, 20hrs is a bit of a stretch. I have barely enough time to do my school works. The peer tutor job was a walk in the park as we were being paid by the college to lead group studies from courses we were already doing. So it’s just like getting paid for studying while helping your classmates. The fast food attendant job was more labor intensive.