I would just say that I think the idea that proper ideological indoctrination of youth is a thing that would fundamentally stick to the human mind throughout their life with no reason to question it usually never really turns out to be true. The brain reacts to stimuli, and human experiences will almost always clash with an officially rosy state-sponsored narrative of reality. A German kid might be taught that he is biologically superior and lives in a great German
rechtstaat where each Aryan son is looked after, but when he’s out in the forests of Belorussia slinging a rifle in the mud and cold or installing toilets for some NSDAP or IG-Farben executive, he’s going to grumble. And sullen grumbling can lead to dangerous conclusions.
The best example of this would probably be the United States. For centuries, the white settler population was indoctrinated with the catechisms of white supremacy and the extermination or enslavement of others. While racist feelings were prevalent, it didn’t create mindless drones who were completely beyond any sort of redemption. Contradictions in the official ideology caused changes among some sectors, and competing interpretations of just how far white supremacy should go (chattel slavery versus free labor, etc.) driven by economic transformations occurred. Things changed and developed from there.
The USSR didn’t collapse because of lack of ideological purity or fervor. Plain apathy was a factor, but a factor downstream of the actual lived experience of its citizens versus what the state-sponsored image of life was. Grumbling and disillusionment because officially you were building socialism but unofficially that appointment you made to fix the faucet is three weeks late and you don’t have the party credentials to speed up the process. It also required the willingness of the nomenklatura to put up the USSR on the international marketplace. That process was downwind of failing economic returns bringing a crisis period.
The same would apply in Nazi Germany, theories of innate human tribalism notwithstanding. You might be educated as a kid that you are great and live in a utopia of genetic supermen, until the necessities of the economy mean you get thrown into a shell factory with shitty pay and a foreman who is constantly denigrating you for wanting to take a thirty minute lunch break instead of a ten minute one. And the labor demanded for maintaining a multi-continental völkisch reich will generate a lot of shitty jobs and unfulfilled expectations that contradict the official ideology.
Our friend Donald Duck is actually pretty instructive on this point. “
Welcome workers of Nazi Land. What a glorious privilege is yours to be a Nazi. To work 48 hours a day for the Führer.” You can lambast the population with official ideology, but if the bread is crusty and the working conditions suck then good luck maintaining that façade. The daily lives experience will be bitter with conscription for far flung occupation duties and the associates psychological toll, economic bust in the years following the war with cartels dominating the market, power struggles among the elite, citizens getting chosen by lottery to leave their homes and livelihoods to go east and start small private farms and estates, etc. It was more effective in the pre-war because it contrasted itself against the world that was made around it. It sought to reverse the “aberration of Versailles” and cleanse the nation so it could be strong. It further benefited from its initial victories in the war. But if you have created your ideal Reich and still things aren’t a paradise, things become trickier.
All this is to say that ideological indoctrination only works if the official state narrative meshes with lived experience. Bread and circuses are primary, and ideology works on top of that to further bind the population into the system. If they aren’t content about day to day humdrum of life, then there’s no reason they would choose to wholeheartedly buy in. If they are then it’s far easier. So instead of asking how we could get stronger ideological programs, a better question would probably be how living conditions could improve for the statistically largest part of the citizenry.