US Law (local/state/federal)

The president should be stripped of any criminal immunity, and should have no protection from being investigated or charged, even while in office.

Pardon power should be eliminated, or at least severely limited.

Money isn't speech, campaign finance laws are allowed, buying elections is illegal.

The insurrection clause of the 14th amendment is clarified to be self executing. Insurrection should also be very clearly defined.

Officials in all three branches of government must publicly disclose their finances and either divest from any potential conflicts of interest or put their investments in a blind trust.

Not sure how to address the executive branch ignoring the law and court orders. At some point you have to rely on people actually enforcing the law, and any mechanism you put in place to stop someone like Trump needs to be carefully considered so that it doesn't just become another weapon to be used by fascists to attack any administrations they oppose.