Anxiety

Hypervigilance is rough. I've been to various types of talk therapy and what has helped the most is somatic therapies - therapy that deals more with the body and processing emotions as they occur physically. People who have been through traumatic events often stifle what they are feeling, to the extent that often it can be difficult to even put a name to the emotion you're experiencing. I remember early on my therapist would ask me, "And where are you feeling this [pain/anger/sadness] in the body?"

When you're out and feel this sort of hypervigilance, try and remember that question. It helps rebuild those connections and gets rid of a lot of that floaty, anxious sort of feeling that comes from being ill at ease.

wear a hoodie and keep moving. certain areas are worse but walking with confidence makes you appear less approachable. got robbed 40 years ago. wrong part of town.

I imagine you already have but have you tried sun glasses and headphones? I find the headphones usually give me an out of most conversations and even though sunglasses typically get me more looks I don't feel as awkward about making eye contact

So this is called agoraphobia, literally "fear of the market space" but more colloquially, fear of being outside. Its frequently paired with panic disorder and in your case apparently with PTSD. I'm not sure I can tell you what to do to make it easier as each case is distinct, but the general thing that needs to happen is that you gradually expose yourself to the thing you fear for longer periods of time until your brain accepts that it is safe to do. Of course you want to only go to expose yourself to places where rationally you know it is quite safe even though the frightened part of you doesn't believe it. This is where your trauma needs to be taken into account.