Hey nickvdk, I think Jerome is on the right track with the custom event approach via the SDK.
The only way I can think of to make this work reliably is to have the Content Card click logged as a custom event via the SDK, with a standalone IAM campaign triggered off that custom event. The key thing is making sure users already meet the audience criteria for the IAM before they start the session where they see the Content Card.
At the start of a user's session, Braze delivers all eligible IAMs to their device upfront. So as long as your users meet the audience criteria when that session begins, the IAM payload will already be on the device and Braze will simply be waiting and listening for the trigger action, which in this case is your custom event firing when the Content Card is clicked.
This should give you that seamless trigger you're after without needing a Canvas.