So - what next? Impeachment?
Absolutely not! just let him twist in the wind for a year, then start a House investigation that will conclude around August or so. No impeachment just the facts out for all to see.
Impeachment is for legitimate holders of the office, not usurpers.
Should be.
I don’t care how many people whine, moan, and worry that “cities will burn”.
Constitutional principal is far more important than any of that.
That's the one and only available constitutional route (other than armed insurrection, federal officers not understanding their oath not needing to meet their grandkids), should the President and/or Congress abrogate the Constitution.