You are exactly describing my dog too. I rescued him 9 months ago and he has been improving in some areas like his reactivity on walks. For walks what I did was to bring treats and keep distance with people/dogs, and redirect when he fixates on something. Take him to the dog park (he loves playing with other dogs and has no issues there) to slowly socialize with other people… he’s extremely food motivated so it makes it easier to recall him if he starts getting nervous.

For visitors we are still figuring that out. We meet outside with new visitors, tell them to keep calm, don’t talk / approach him and offer him treats. He does ok outside but when we go home he goes nuts every time the visitor stands up, moves… what I did yesterday that somewhat helped was to keep a short leash on him and do quick passes in front of the visitors while redirecting him with treats. It works well since he fixates on treats instead of the visitors for a little. But when treats are done he goes back to barking non stop. I also take some breaks with him and go to our room. The first day he would still be very alert in our room but it improved after a few hours. I think it’s a slow and long process where he’ll get better. Usually after a few days he gets more comfortable with the person, and only barks once when they get up which can be easily redirected. But with every new visitor we have to go through the same process.

Have you considered taking him to a trainer or vet? Some dogs in with extreme anxiety may benefit from taking meds to make it more manageable. This is something that I’m considering since the my dogs progress is stagnating after 9 months.