Thanks Jan. It will be good to know what happens in practice.
I found this (translated by Google) in today's (Nov 10th) Haniotika Nea, which sounds reassuring:
"The problem of entering retail stores and restaurants was faced by several citizens from third countries (ie countries outside the European Union) who are vaccinated but their certificates are not "scanned" by the Greek application, nor of course can not obtain the european pass .
The solution to the issue of control of vaccination certificates from third countries was given yesterday by the Ministry of Development and Investment, in which it is clarified that "the entry and service of foreign clients who have a vaccination certificate or recent illness from a country outside the European Union is allowed of the paper certificate and demonstration of a proof of identity (passport), without the need for verification with the special application COVID Free GR. "