[voltagex_]

Can I get something that would allow me to unlock an SSH key by tapping a card to my phone?

[j_s]

https://grepular.com/An_NFC_PGP_SmartCard_For_Android

I believe you would still have to write most of the software involved yourself. A discussion of smart card login with SSH as of five years ago:

https://grepular.com/Smart_Cards_and_SSH_Authentication

And a useful discussion on SSH and 2FA last year here on HN: https://news.ycombinator.com/item?id=10885654