Welcome to the forum. Firstly, It's so sad you have so recently lost your dog. A pet is certainly a great joy & comfort, & they do indeed become friends in our lives, so losing one is very painful and we grieve for them. I try to remember the good times I had with my cat, nevertheless I still miss her & always will.
It is an important step you have taken to come & talk here. I think you don't want to remain 'stuck' where you are. Knowing that is also an important idea to hold on to.
I can relate to the feelings of anxiety around meeting people, & it usually takes me a long time to feel comfortable with individuals I regularly meet. I, too, do not have many friends or close family. & have had some very tough times over my life. One attempted exit, very long ago.
Your title for your thread caught my attention. I wonder if you would like to say more about the idea of being a ghost?
I also would like to ask, would you consider talking to your GP, maybe getting some advice about how you might like to get help, with a Psychologist or Psychiatrist?
In the meantime, talking here is fine. I've looked around here, & I think you are not alone in how you feel. Indeed, I might feel very much as you do.
I wonder if it is your discomfort about going out is COVID related? Mine is, but only in part.