Do you mind sharing why you don't want to go to a clinic? Is it fear of being spotted there or more just looking for convenience?
I didn't know there was such a thing as home test kits for STIs. My first reaction was it's probably much better to go to a clinic. I assume that would have less chance for error. And based on my last visit to a clinic (I also was just looking to get a clean bill of health at the time), I think there's so many things you can be tested for, they can recommend what tests should be done based on which STIs are currently prevalent and your history. But on second thought, it seems like a good thing that these exist to encourage people who won't go to a clinic. I wonder if you're having trouble finding them in Canada because HealthCanada hasn't approved them or something.
There's this service for a variety of STI's. But you still have to drop off the test kit at a lab, in person.
Home - TeleTest.ca
There's also this one, but it's only for HIV currently. They are planning on rolling out other STI tests sometime this year.
GetaKit
I found those links through this study about home tests for STI's:
A review of internet-based testing services for HIV and sexually transmitted infections (STIs) | The Ontario HIV Treatment Network (ohtn.on.ca)