As of Sunday 01.05.2022 and for as long as the epidemiological data allow so, all travellers arriving in Greece, regardless of their country of origin, are no longer required to display a valid certificate of vaccination or recovery from COVID-19, or evidence of a negative test result from SARS-CoV-2 infection (PCR or Rapid Antigen test).
This is stated on the official Facebook page of the Embassy of Armenia in Greece.