The Ministry of Digital Government announced the release of two new applications. One is called Covid Free GR and its use seems to be very simple: to save a document in the wallet (which is the second application, you have to scan the QR code in the application, or upload it as a pdf file.
The "Save to wallet" option will appear immediately afterwards.
The Ministry of Digital Government states on the application page:
The official applications verification and storage in Wallet format of European digital COVID certificates (EU Digital Covid Certificate) και εθνικών βεβαιώσεων COVID διατίθενται μέσω του επίσημου λογαριασμού της Ελληνικής Δημοκρατίας και δίνουν τη δυνατότητα σάρωσης, control and their storage.
The new application is available through covidfree.gov.gr as well as through Apple's App Store and the Google Play Store.
Download the verification application | Download the Wallet app | Instructional video | Space signs - COVID-free badges