For Canadian OTT (as in OTT services from Canada in Canada), the only one I know of that actually exists is Cravetv.ca (which is run by Bell). It is designed to compete with Netflix but mostly does so by taking advantage of the duopoly that exists in Canada for TV. Bell owns enough of the content providers in Canada that they can effectively prevent Netflix from being able to get that content for distribution in Canada.
Rogers & Shaw did attempt this with ShowMi but they shut it down. More accurately, when Shaw got bought out by Chorus Entertainment bought Shaw, they shut it down.
Since there is no Cravetv app on Roku, I've never tried it.