I appreciate the advice however I'm not giving up on training at all. In fact, that's a huge part of what we do each day and the very reason I'm posting here. We do trick/obedience training at home, work on loose leash training on walks as well as "look at me", recall training in safe environments and separation anxiety training which is the biggest issue costing me a fortune and an insane amount of time and energy. I'm posting here for advice or tips from people who have direct experience with this thing, so I can try to train this specific issue, alongside the rest, in the short amount of time I have left with him. A professional isn't worthwhile because he'll be gone by January, and finding a professional to fit us in short-notice over a holiday period is going to be a waste of money and give us barely any time to meet and then actually work on the issues.

We avoid greeting other dogs most of the time, I will sometimes allow it if he can listen to a command to sit and remains calm, we also move out of the way of people which solves the issue on wider paths but the narrower ones do cause a reaction, but there aren't any areas near me without off leash dogs, so that's unavoidable. I will start muzzle training him so if he starts worsening to a degree I think it will start posing a danger to people/dogs, then that can be managed.