One thing most people outside (or inside) the US don't realize is how much power is allocated to the individual states. You probably won't see an outright ban on things like gay marriage or interracial marriage at the federal level early on. You'll see the Supreme Court roll back the protections. Certain states will then start pushing their own bans. Pretty much what they did with abortion.
Remember, a lot of the Nuremberg Codes were based on Jim Crow Laws, so we can look into our own history. Jim Crow laws didn't always specifically mention black or white people. The relevant states or municipalities used selective prosecution and over the top sentencing to target black people. They also made public services too onerous for black people to use, or provided a "black" version of things like parks and pools. We saw updates to this when the "preclearance" clause of the Voting Rights Act was struck down by SCOTUS in 2013. Roberts said "it wasn't necessary" even though a bunch of states had trigger laws that were written year ago to go into effect in the event of that very ruling.
As for concentration and labor camps, we've always had those. The current era Republicans are just ramping them up. Shipping people who commit civil violations to Gitmo as well as expanding the ability to force prisoners into labor are bad portents for this. Add in the fact that our 150+ year old understanding of "Citizenship" just got thrown onto the pyre, and the right is very much looking to create an underclass of non-people.
they are also doing a lot of trumpery (teehee) the Nazis engaged in. The ostentatious displays of a very vague yet stringent version of Christianity. The almost cartoonish admiration of signs of physical strength. Traditional gender roles. Attacking education and arts. A reverence for an imagined past. A cultish worship of the military. Well certain parts of the military.
