A dedicated Portfolium Pathway LTI would be nice to have that automatically enrolls students who launch from Canvas. I could see an administrator create one for each program that would allow SSO into a particular pathway. Either a unique url or custom parameter would map to the correct pathway.
The options right now to populate Pathways is via an unauthenticated link or pasting in email addresses. A LTI Pathway link could be added to every course and serve as a reminder for items that should be posted to the pathway.