Dear @Paul-Reed ,
can you maybe add me as a contributor too to that branch?
You are a member already.
Afraid not, I'm a contributor to the branch and not a collaborator, so I can't carry out any of the admin functions, such as accepting PR's or adding additional collaborators.
By their own admission, they are not so familiar with GitHub. So maybe they need a little coaxing to help get the PR merged.
Rather than complain about it here, have you contacted the owner privately to see where things stand?