Sure, I refer you to the body of evidence presented at the impeachment trial of Donald Trump that demonstrated that he has worked with foreign governments to illegally influence US elections.

The impeachment was not over the 2016 election.

I point to Mueller report which looked for collusion between the Trump campaign and foreign countries and found none.

That's just it, though. The Mueller report found tons of collusion and obstruction of justice. It deliberately referred those to the Congress.

I challenge your assertion that the report found no collusion. You have not read the unredacted report nor has anyone outside of a select few in govt

That's not true either, the investigation resulted in 34 indictments.

indictments for...

Americans were indicted for lying to Congress, lying to the FBI, witness tampering, and a few other crimes related to inconsistent testimonies and lies, etc. And of course a bunch of Russian nationals were "indicted" for "crimes against the United States" type things but nobody is under the illusion they'll actually be prosecuted.