KGpg is a simple interface for GnuPG, a powerful encryption utility. It can help you set up and manage your keys, import and export keys, view key signatures, trust status and expiry dates.
but do they "have agreed (to some degree) to be a part of this working group and work towards improving the usability across the PGP eco-system"? it's the one criteria to be part of the list.
https://www.kde.org/applications/utilities/kgpg/
KGpg is a simple interface for GnuPG, a powerful encryption utility. It can help you set up and manage your keys, import and export keys, view key signatures, trust status and expiry dates.