Answer by mblythe for Change pinentry program temporarily with gpg-agent

Looking at man pinentry-gnome3, I see this:

   pinentry-gnome3  implements  a PIN entry dialog based on GNOME 3, which   aims to follow the GNOME Human Interface Guidelines as closely as  pos‐   sible.   If the X Window System is not active then an alternative text-   mode dialog will be used.  There are other flavors that  implement  PIN   entry dialogs using other tool kits.

Unfortunately, this text-mode fallback doesn't work for me. It seems others have the sameissue. However, this comment spurred my to try a different GUI pin-entry program: pinentry-gtk2. You can switch like this:

> sudo update-alternatives --config pinentryThere are 3 choices for the alternative pinentry (providing /usr/bin/pinentry).  Selection    Path                      Priority   Status------------------------------------------------------------* 0            /usr/bin/pinentry-gnome3   90        auto mode  1            /usr/bin/pinentry-curses   50        manual mode  2            /usr/bin/pinentry-gnome3   90        manual mode  3            /usr/bin/pinentry-gtk-2    85        manual modePress <enter> to keep the current choice[*], or type selection number: 3update-alternatives: using /usr/bin/pinentry-gtk-2 to provide /usr/bin/pinentry (pinentry) in manual mode

Once I switched, it worked perfectly for me! In a terminal on the desktop, it will use the GUI password entry, but when I ssh into my machine, it will use a text-mode password entry.