Yesterday, over a Clean Monday fish lunch by the harbour in Chania, a friend, who is flying back to the UK with Ryanair shortly, was talking about the two recent crashes of Boeing 737 Max 8 aircraft, leading to them being grounded in or being forbidden from entering the airspace of some countries and the fact that Ryanair fly Boeing aircraft. He was clearly a little concerned, which prompted me to do a bit of a search of who is flying what.
As far as I can tell, of the main airlines that I know fly directly to Crete in the summer, only Norwegian operates any Max 8 aircraft. Obviously, that doesn't necessarily mean that they will use them to fly to Crete but they might. Ryanair and Jet2 do operate Boeing aircraft but not the 737 Max 8 model and Ryanair don't seem to mention it in their future plans. They only operate Boeing 737 800s and all their current future orders are the same although they do have options on some Being 737 Max 200s. Aegean, Olympic and Easyjet do not seem to use Boeing aircraft at all so it is unlikely they would adopt it. I am sure there are other airlines that fly to Crete in the summer and you can easily find what is in their fleet either from their own web pages or from Wikipedia.
I also did a quick check of some of the main European airlines that fly into Athens including BA, SAS, Finnair, Air France, KLM, Lufthanza, Brussels and Alitalia and none of them operate Boeing 737 Max 8s. I didn't check subsidiaries or look at the charter companies.