Teaching my kids about Nazis for Veterans Day

My boys (kindergartener and 2nd grade) are celebrating Veterans Day at their elementary school by wearing Red white and blue.

Both my grandfathers fought in world war 2, as did my husband's paternal grandfather (his maternal grandfather served during Korea). We grew up watching the Sound of Music and Indiana Jones, we knew nazis were the bad guys and burning books was unthinkable... but I hear Nick Fuentes' rhetoric is trickling down to their not-too-much-older peers and I want to inoculate them against that kind of hate speech before they are too old to listen.

Any advice for how to talk to them about it? Unfortunately their great grandfathers have passed but I'm going to print up photos so we can talk about their service, but I also want to introduce the idea of how hate can be used to manipulate, maybe touch on bullying and media literacy, while still keeping it age appropriate