I figured out how to create a link that goes to a card using webhook/API data, but it picks the WRONG card.
Widget Link (WORKS!):
Card Link (YIELDS 403):
Card Link (REDIRECTS TO WRONG CARD):
The second link probably shouldn't work, so this may be intended behavior.
However, that final link does everything I'd expect except actually show the correct card. It loads the Favro webapp properly, which then proceeds to convert that URL into the standard https://favro.com/organization/:organizationId/:collectionId?card=:shortId, but the collectionId and shortId have no relationship to the cardId used.