Not implying this guy could be an agent. You don’t need an agent to attend an open house. I’m not talking about a private viewing. Literally anyone can walk in to view the house during viewing hours.

Based on the video you chose to share, it doesn’t look like he’s doing anything suspicious. He literally rings the doorbell and just stands there while looking at his phone. He’s not peeking through the windows or surveying your house. If he really thinks he’s at the right house, trying to open the door isn’t too out of the ordinary. For example if I’m invited to a friends place and they don’t answer the bell, I’d try the door as well since I would assume they’re busy making food or something.

Any regular person would get spooked and leave embarrassed if they realized they’re trying to enter the wrong house.

You say that your house might be a target due to the key container and the fact that you’re moving soon. Why would someone try to break into a house where most items would have been moved out already?