I am an Implementation Specialist for a content publisher.
During the "Tips for Implementing LTI 1.3 with Canvas" livestream with Karl Lloyd on November 19, Karl mentioned that Canvas did not currently support selecting multiple resource links or line items concurrently. We were surprised by this, as we've been doing it with our Canvas integration for the last several months.
We were early adopters of the LTI Advantage standard and have been supporting it with Canvas since December of 2019. If Karl or anyone else on your Product team would be interested in discussing what we've done with our integration, our technical folks would love to talk. We might be able to provide some insight into the challenges and successes we've had working with Canvas, and would appreciate the opportunity to future-proof our own integration with a better understanding of how Canvas plans to approach LTI Advantage integrations in the future.