Anyone know of a portable document scanner that works with the new M1 chip Mini Mac?

You probably already have one.

I have not used the flatbed scanner in my multifunction printer in a long time. Why? Because the iPhone works amazingly well as a scanner.

I use the Notes app, click Camera->Scan Documents. It uses AI to get the proper document edges and adjust for the angle of the shot. Makes a multipage pdf in a breeze.