I don’t think it will be easy and it definitely won’t be cheap. I had a quick look at the big players I could think of off the top of my head (Bell, Rogers, Telus, Fido(owned by Rogers), Koodo(owned by Telus) and Virgin(co-owned by Bell))
Koodo was the only website I could easily find what you are looking for. I have no idea what a SIM costs. They had a prepaid plan for $15 and then a data “booster” which you could add. I could not find anything that offered a data only plan without a contract. That doesn’t mean they don’t exist, I just didn’t spend more than a couple of minutes looking per website.
It will also be highly dependent upon where you are in Canada. Your choices are going to be much more varied in Toronto, Vancouver and Montreal than they are in Flin Flon.
I would email the providers with what it is you are looking for and compare it to the Canada rates from your current provider. You may be further ahead roaming.