Official US policy is that Americans have nothing to fear. There are no explicit laws preventing American Citizens with brown skin from working in a school for example.

The US hasn't reached the level of "Law for the Restoration of the Professional Civil Service" or "Denaturalization Law" yet, although you can easily see it's on the cards. The Brownshirts were around over a decade before then

Except this admin doesn't seem to strongly care about laws.

It is more than willing to implement its extreme nationalism via executive orders, regardless of what the law says.