Just as not every vegetarian environmentalist is Hitler (yes, I know some of them are wannabes), not every irredentist nationalist is Hitler either. Hitler picked up his rhetoric straight from the modern inventors of this mania, the Italians. And by Italians I don’t mean Mussolini. The very term “irredentist” comes from “Italia irredenta” - unredeemed Italy.
Cavour, Mazzini, Garibaldi and that lot were the rather more respectable founders of the fad, that got picked up by every would be demagogue and two bit politician in central and eastern Europe before WWI. It was a fad among liberal intellectuals all over Europe.
And Putin’s brand has its own Russian-Slavic intellectual roots (Slavophilia), which come from that old 19th century liberal fad.
I would venture a guess as to what that means to us today. A primitive, earthy, pagan, nationalism that seeks to cast off civilization (Christianity) and seek to live like the phony-baloney "noble savage" imagined by Rousseau.
Am I at least close?