You may indicate your identity to the receiver. Use at most 4 lines with 20 characters each.
We need a findable recipient. You should include a name and a location indicator. Use at most 4 lines with 20 characters each.
If you value your privacy, you will have to use end-to-end encryption on your end. But even then we need to collect metadata (i.e. recipient) in plain text to deliver your card.