Can Rise be purchased separately?

Thanks, Christian. That's helpful! If you're using Rise, have you also looked at publishing to Review? That is a great way to allow SMEs to make comments on the course as they interact with it, and it'll create a screen capture of what they see when the comment is submitted. 

Also, if you're using a 360 Teams account, you could look at adding your SMEs to a seat and inviting them to collaborate on a Rise course to make edits.