The “Save securely on device” option to store the password for Threema 2.0 for desktop (or Threema Work 2.0 for desktop) may be grayed out on Linux devices. If you are running a window manager other than Gnome or KDE (e.g., Sway), you
will need to export the environment variable XDG_CURRENT_DESKTOP=GNOME
or XDG_CURRENT_DESKTOP=KDE
in order to use GNOME Keyring or KWallet through the “Save securely on device” option in Threema and Threema
Work.
You can make this variable permanent using an application like FlatSeal, or by using the following command line:
# Threema flatpak override --user --env=XDG_CURRENT_DESKTOP=GNOME ch.threema.threema-desktop
# Threema Work flatpak override --user --env=XDG_CURRENT_DESKTOP=GNOME ch.threema.threema-work-desktop