While investigating The president, Mueller discovered that the Trump kept an unauthorized, undisclosed and unsecured server with classified, government information in Trump tower. And it had been hacked by foreign governments. While the server was being subpoenaed, The president had it wiped. And not with a cloth, with bleach bit. Deleting over 30,000 government related emails. To further eliminate evidence, the President personally destroyed his hand held devices with a hammer. After that, the Trump campaign paid a foreign agent to find dirt on his opponent. Then asked the FBI to investigate his opponent for colluding with the enemy. And the FBI agreed to do it.
My response would be that it would have been about the 38th worst thing Trump has done. The media would likely cover it for a day or two until he did something else insane to change the story.
To answer your second question, probably doesn’t rise to impeachable offenses. Probably should get an indictment after he leaves office though but that depends on many details you didn’t go into.
Without due process? Without the presumption of innocence? Without charges or even evidence of a crime? Which one of these are you willing to eliminate in order to lock up the president?