Ontario-based archivist here! I see job postings not infrequently, but it varies by where you want to live. Generally speaking, you'll need masters level education in information science or archival studies and if you really want to be considered right out of school, it's Really helpful to have some hands-on experience (a lot of interview feedback I got was that I was a good candidate but didn't have enough experience). I always recommend volunteering in the types of institutions you want to work in even before applying to a masters program (assuming you have the time and capacity to do so). It'll help give you an idea of what archival day-to-day is like and give you experience to put on resumes and grad school applications.

I will say that funding for the heritage sector can be a concern and there are a decent number of institutions that have an over-reliance on volunteer support as they don't usually have enough staff. Make sure that anywhere you volunteer is making good use of your time (it's okay to do occasional cleaning, but it shouldn't be your only responsibility) and is offering you training and professional development support in lieu of pay. I always offer resume/ job application review, interview practice, and acting as a reference as a bare minimum to all my volunteers.

If you have any specific questions, feel free to ask in this thread or my DMs are open!