> they asked family members to sign that their relative died from covid when dying from something unrelated otherwise they are not allowed to retrieve the body for weeks.

At least in the UK and US this is misinformation and false. Cause of death is certified by doctors or coroners and added to a database that reported COVID deaths are pulled from. Family members do not have to sign anything before cause of death is determined. I'd wager that Greece is no different.

COVID deaths are well known. There are many scholarly articles out there on how they are counted for people who don't get their information from Facebook. Here's a quick little article for example. https://www.scientificamerican.com/article/how-covid-19-deat...