Many jurisdictions I believe have what is called a "Statute of Frauds" which dictates that all real estate contracts must be in writing. Automobiles are not real estate. If I verbally offer $10k for a car and the dealer says, "fine", then a verbal contract exists and is enforceable. The power to impeach rests solely with the House and they have exercised that power.
I certainly don't recommend verbal contracts when significant amounts are involved, as enforcing such a contract can be difficult.
As for California, last time I checked the transfer of ownership of real estate does not take place when the contract is signed. It takes place when the seller delivers the signed deed, typically to an escrow company. This detail can significantly effect any controversy that arises during the sale. There is an ugly story in my past that explains how I know this.
Trump has been impeached. To believe otherwise is to believe that the decision on whether or not to impeach Trump rests solely with Nancy Pelosi. The Constitution has no mention of "the Speaker of the House" nor does it grant any powers to such a person.
And the formal document transmitting the articles of impeachment to the Senate is the equivalent of the signed deed. The "statute of frauds" is of very recent vintage...the authors of the Constitution would not recognize it. The functioning of Congress is and must be more formalized (and always has been).
There are many things in the internal rules of the branches of the Congress that are not specifically mentioned in the Constitution, which wisely leaves those up to the membership of those bodies.
The House has voted on articles of impeachment. Statutory impeachment, however, has NOT happened until the Senate receives the official documents of that process.