Greece has achieved more football wise than all these countries combined in the last 20 years , doesn't mean they have better players.
Norway, Denmark and Sweden have and had a decent amount of players that perform at the highest level of club football, can't say the same about those two although I must admit what Iceland managed to do a few years ago was seriously impressive.
(Now that you mention it an Eastern block super team could probably rival the very best)
Iceland in the 2010s were basically a Northern Ireland type team who were incredibly organised and then in final third you had a matchwinner in Glyfi Sigurdsson who based on his premier league seasons would be making a Nordic combined squad. Iceland were always going to slip back to 4th or 5th in the group given the population but making a World cup on top of Euros 2016 QF was a sensational period for them.
Ironcially their best squad was probably in the early 2000s when they used to finish bottom of qualification groups, Eidur Gudjohnsen the star but they had a solid core of players in premier league, Gudni Bergsson, Heidar Helguson and Herman Hreidarsson are guys I can remember as solid pros.
Similar to Finland. Early 2000s had a spine of Sami Hyypia, Tainio, Kolkka , Jari Litmanen and Mikael Forrsell who all played to very good standards for big european teams. Also had a choice of Antti Neimi (Finnish not Scottish....
) and Jussi Jasskelainen in goal, both were top 10 prem keepers at the time.
They never really got close to making international tournament in those times bar a year of Roy Hodgson managing them.
So I think both benefited from Euros being expanded to 24 teams although Iceland making the following World cup showed they were capable of making it if Euros had stayed at 16 teams.
