Kobo recently started adding download info to the product info section at the bottom of each book page.
If it's available for direct download, it's supposedly indicated with the format and DRM status, e.g., EPUB2 (Adobe DRM) or EPUB2 (DRM-Free). The tricky part is, if it's
not downloadable (and therefore likely EPUB3 with or without DRM),
it says nothing at all 
I don't know how accurate Kobo's product info is. Would be interesting to know if it's as reliable (or unreliable) as the blue "download epub" button.