isn't a closed implementation adversarial to those benefits? I mean any implementation can handle the signing etc, as the operations are an open standard. But

isn't a closed implementation adversarial to those benefits? I mean any implementation can handle the signing etc, as the operations are an open standard. But running the actual pgp implementation on a system you have no access to sources, can't really see the advantage of just using an old laptop to have truly airgapped system (plugging your proprietary device on a connected computer doesn't look that airgapped to me)