You see, in a number of these countries, they never really had an actual nation. They were always a part of some empire or duchy or whatever. The real nation-building process was quite recent. Since they never really had a history as a nation, they had to build a nationalist project more or less out of thin air or at least out of castles of sand.
Hence the national heroes of these places goes back to World War 2, when the Nazis promised the Baltics, Belorussians, and Ukrainians with independence from the USSR. The USSR had just recently taken over the Baltic states in order to have strategic depth against the Nazis. The Ukrainians had been independence-minded, at least in the west, since the Bolshevik Revolution. These nationalists claimed that the USSR and Russia have always dismissed the idea that they have separate countries. While in the USSR, nationalist aspirations were largely forbidden and played down.
After the USSR took the Balts away from the Nazis and incorporated them into the USSR, they lost the independence they had had during the interwar period. They claimed that the USSR did not allow them to develop their national languages but that does not seem correct. Anyway, the USSR and Russia were always seen as the thorn in the side of the national aspirations of these peoples.
Since they never had much of a recent history, most of the nationalist heroes of Belarus, Latvia, Lithuania, Estonia, and Ukraine end up being some nationalist Nazi collaborator from 1942 named Vyashlev the Jewslayer or something along those lines. There are statues and monuments to these guys all over these countries with the exception of Belarus. At the same time, all of the Soviet era statues, including to heroes of the Great Patriotic War, have been torn down or vandalized.
The Litts (Lithuanians), Letts (Latvians), and Ukrainians were the biggest Nazi collaborators of all of the national groups in the region.
Poland and Finland are extreme Russia-haters for nationalist reasons, but the Poles don’t like Nazis, and I don’t think the Finns are all that Nazi. Poles hate Communism, in part for religious reasons of extreme Catholicism.
In Hungary, the right wing has Nazi tendencies. The Hungarians had a sort of nation long before the modern era. A fascist dictator named Horthy ruled Hungary in the interwar period and during WW2. I believe he was a Nazi collaborator. The leader of Hungary, Victor Orban, has praised Horthy. The nationalists here are Nazis, but they are not a large movement. The party is called Fideliz and its origins are in the Red Arrow of WW2. They are Nazis.
Romanian nationalists are descendants of the Iron Cross of WW2, but they are not very popular for some reason. I believe Romania has been a national idea for some time. Also, they are Orthodox. Czechoslovakia is another national idea that has been around a long time. Nationalists are not popular in either country, as you can see in the amicable breakup they had into two separate states.
Belarussian nationalists are Nazis, but they are not popular. They only get 20-25% of the vote. This is because Belarus is rather new in terms of national ideas.
Croatian nationalists are absolutely Nazis, descendants of the Ustasha collaborationist regime. That’s why Communist Yugoslavia cracked down so hard on them. They are also Catholics. The recent president Franz Tudjman was absolutely a fascist, though I don’t think he was a Nazi. Over there, Croatian nationalism often just boils down to “Serb-hater.”
There is a racial aspect to Ukrainian nationalism. It holds that the true Ukrainians are a sort of Aryanized Germano-Scandinavian people, descendants of the Kievan Rus, which was after all settled by Swedes.
The others, the Slavs (Russians) are simply undermenscen to be destroyed. So they copied Nazi racial ideas and said that they were not Slavs to get away form Nazi anti-Slavic theory. The Slavs were hated by the Germans mostly because the Nazis saw all of them as Communists. They were also said to have a “slave (Slav) mentality” (see Nietzsche) which made them too weak to resist against Communism. The Ukrainian nationalists also saw Russians as Communists.
Ukrainian nationalists hated Jews because they saw the Jews as the leading edge of Soviet imperialism (anti-Ukrainian nationalism) and Bolshevism. In other words, they were following the Judeo-Bolshevik theory of the Nazis. It is true that Ukrainian Jews were passionate Communists at this time, in part because the USSR cracked down so heavily on antisemitism.
As I mentioned earlier, Ukraine or Malorussia (literally Small Russia but in this context Central Russia) has long been seen as a land of bandits and robbers, a lawless place. This tradition continues today with oligarchs robbing the place blind. An anarchist named Makho was a Ukrainian in the Russian Civil War. Originally allied with the Soviets, he turned on them during the war and led and anarchist rebellion. Makho is also seen by Russians as a typical Ukrainian. He was a bandit before he was an anarchist, and anarchism is associated with lawlessness and chaos, hence he’s an archetypal Ukrainian.
There is another culture war going on here, and that is the Roman Catholic West versus the Istanbul (or Antioch) Eastern Orthodox. Few people realize this but the Catholic Crusaders killed as many Orthodox Christians in Palestine as Muslims. They were seen as heathens. Afterwards, another sort of Catholic crusader in the form of German crusaders attacked the Orthodox communities to the northeast. And it looks like they converted them to Catholicism while they were at it. The German crusaders saw the people to the northeast as forest-dwelling barbarians and heathens.
Western Catholics again attacked the Orthodox in the East under Napoleon, and once again were beaten back. The result in part was two Russian borrowings in the French language – bistro and douche (the original French “water toilet”).
The Germans in World War 2 and their Roman Catholic collaborators were seen as another in the line of Western Catholic attacks on the Orthodox East.
In Ukraine, this also has a religious form as the Ukrainian Orthodox Church split from the Russian Orthodox Church at some point and became what some see as a heretical schismatics. They adopted a sort of “Greek Catholicism” (I’m not even sure what that is, but supposedly it’s a heretical schismatic split from the Orthodox) and allied themselves with Roman Catholicism and the West against the Russian and Russian Orthodox Church of the East. The Ukrainian Nazi nationalist battalions often attack Orthodox churches for some reason. I’m not entirely sure why they do that.
So as you can see, there is a lot of history going on here.