Hi! I am also a Queen’s graduate (2021) and I took an online course through queens this year as a prerequisite for UofA. It was super easy to sign up as a non-degree student but they don’t have a ton of online class options. I think some people on this forum have taken online courses through Athabasca to boost gpa.
If this helps I also don’t consider my gpa to be competitive. Last year I was rejected from McMaster and McGill and waitlisted to Western. This year I was rejected from Western but accepted to UofA! So try and stay positive I think some schools put less value on gpa