Questions about the transfer of a privately sold car

Hello, I am currently selling my Opel Astra K and would like to achieve the following: 1. The transfer should pass through the buyer, who travels to me and then “takes” the car. 2. The transfer to a different federal state than mine. 3. The car should not be registered with me during this journey. I would like to log it off beforehand. I can achieve this with a short-term registration mark, which the buyer applies in advance in his city and then arrives at my place, right? For this, insurance is necessary to get this short-term registration mark, the journey is insured with it. Do I understand that correctly? Or do I have a mistake in thinking? Thanks in advance! Ciao Defcon0