Is it possible to insert a partial into a card deck?
Assume you are talking about Foundry?
Answer is no. I think. But you can add what I think is called a Card Slice, which is really just a drop zone, and add a partial to it.
I think. I don’t use Foundry much. But i think that’s how it goes.
As @TemplateRepo already said, you can add a “card slice” to the card, this is a regular drop zone which works with (almost) any other stack. This works also with partials: