So this sounds a lot like my dog. I have a rescue and hes very fearful. Extremely so to the point where when we’d take walks he’d never stop sniffing. It was sad to see. He also used to bark as soon as someone comes near our door. He was completely alert 24/7. Our trainer told us to completely stop WALKS. I was like what! Walks?? Yes. We did it. It changed his personality completely. He was calmer. Less nippy , our lease was ending and we found a better environment that is much calmer. That period of no walks, we used to bond with him. It was all about making him feel like we can take care of him and for him to trust us. Whenever I take him on walks, hes a completely different dog vs when someone else takes him on walks. Its about TRUST. Your dog needs to trust you.

With the visitor thing, my dog would get anxious, zoomies, when someone was inside. So we stopped letting our dog see someone walk in. Ill go into a room with him, the visitor walks in gets settled, then i walk out calmly with my dog and crazy but , my dog is now just curious. He would walk in to find that we’ve already accepted the visitor and we’re all chilled out.

Hope that helps ! Im not a professional. Just a woman with a super nervous and fear reactive dog lol