So after a month we finally got ActivityPub working on Ghost. I would first like to explain the issue.
My blog was flagged under the subdomain that was generated during the install, rather than the actual domain it would sit on. Thankfully, after a lot of back and forth with my hosting provider and Ghost's support, we were able to get this fixed.
I know this is a far shorter article than you are all used to, but I want to thank Sag [Product Engineer] and Bob [Tech Support Engineer] for their amazing work in getting this sorted.
As someone who has used WordPress, MovableType, and other platforms, I am so glad that even without using Ghost's own hosting (as it would be overkill for my needs) I was still able to get real technical help. I just wanted to shout out the amazing team they have over there