The game should actually already have trading cards, I've raised the issue with the sales team and they will investigate it further. Please keep playing, they should appear shortly!
It has and the work fine at least for me.
The realm rejoices as Paradox Interactive announces the launch of Crusader Kings III, the latest entry in the publisher’s grand strategy role-playing game franchise. Advisors may now jockey for positions of influence and adversaries should save their schemes for another day, because on this day Crusader Kings III can be purchased on Steam, the Paradox Store, and other major online retailers.