there was the idea, to create a little webxdc-tool for that purpose - paste a key and get a vcard. however, it was just not done by someone yet 
a general note to understand priorities: Delta Chat does not consider PGP in its classic dealing-with-keys form as a convenient-enough approach to exchange keys. we do not want users to be confronted with key questions in the UI they “reach”, Don’t ask users anything about keys, ever. therefore, effort and focus is put to other parts - autocrypt, secure-join, vcards etc. - resulting in far more messages being encrypted than on most other email apps
but a vcard webxdc could be a nice addon for advanced power users