I recently replaced my older VHF that I could not hook up to my chart plotter to a VHF with built in GPS. Doesn’t cost much more than a standard VHF.
Also got my MMSI number and plugged it into my VHF. In case of emergency, all I have to do is hit the emergency button and my exact position is sent out and my MMSI number identifies me as owner and make/size of boat.
As others have said, most of the time documentation is your choice and state registration is required in most states whether documented or not. I’m in VA, one of the few states where registration is optional for documented boats.