This worked well in gpg version that came with Debian stretch. gpg version that comes with Debian buster invented another confusing useless warning.
gpg --keyid-format long --with-fingerprint patrick.asc
gpg: WARNING: no command supplied. Trying to guess what you mean …
pub rsa4096/8D66066A2EEACCDA 2014-01-16 [SC] [expires: 2021-04-17]
Key fingerprint = 916B 8D99 C38E AF5E 8ADC 7A2A 8D66 066A 2EEA CCDA
uid Patrick Schleizer firstname.lastname@example.org
sub rsa4096/3B1E6942CE998547 2014-01-16 [E] [expires: 2021-04-17]
sub rsa4096/10FDAC53119B3FD6 2014-01-16 [A] [expires: 2021-04-17]
sub rsa4096/CB8D50BB77BB3C48 2014-01-16 [S] [expires: 2021-04-17]
Now showing this warning:
gpg --keyid-format long --import --import-options show-only --with-fingerprint patrick.asc
But that syntax is weird. Super long command for such a simple thing “show me the fingerprint of the key inside that file”.
For Whonix repository, adding Whonix signing key to apt-get there is no alternative to using gpg since gpg alternatives are unsupported by apt-get.