He could be impeached on literally almost anything. The constitution says "high crimes and misdemeanors". You can't wipe your ass without breaking some law in the US.
Impeachment isn't really the end-all be-all we think it is, because you need 2/3 conviction in the Senate to get ejected, which basically mandates that his own party would have to vote to impeach. Clinton was impeached, big whoop.
And then we get President Pence. who unlike Donny may actually govern competently.
Ain't gonna happen IMO.