But, yeah, any state prosecutions (likely especially the first) is going to (1) get removed to federal court, and (2) go through a wringer of federal litigation, likely reaching the Supreme Court, over Supremacy Clause immunity before much substantive happens on anything else.
OTOH, the federal duty at issue in in re Neagle was literally protecting the life of a Supreme Court justice riding circuit, as much as the present Court may have a pro-Trump bias, I wouldn't count on it being as strong of a bias as it had in Neagle.
Therefore there is considerable leverage for allied servants to form an alliance that more or less offers their allegiance in exchange for non-prosecution. I would expect especially DHS to basically become a non-functional (or even seditious) department if they prosecute those guys and they could purposefully make the president look bad by making his security apparatus look incompetent.
Won't help if the prosecuting sovereignty isn't the one they work for (state vs federal charges.)
Also won't work if the agency is disbanded and they are dismissed en masse before the prosecution happens.
Unless, as Doge showed us, you ignore the law, fire them anyway, and the SCOTUS says, "Yeah, whatever."
See where this is going ?
I admit, US propaganda is very good at projecting an image of strength. I strongly doubt it is prepared for a civil ground war, based on all available evidence. It cannot even keep other nation states out of critical systems. See fragile systems for what they are.
If you're imagining a large scale revolt, figure that the revolutionaries will be outnumbered by counter-revolutionaries, even without the military. (Which would also include police forces amounting to millions more.)
https://www.kff.org/from-drew-altman/trump-voters-on-medicai...
https://kffhealthnews.org/morning-breakout/voters-in-trump-c...