This was the year before Covid. But I remember reading the same guidelines that people posted about who can accompany. I did my research and went in.
The way Islamabad embassy works is you have to show up early at a pick up location where you go through some security and then board buses provided by embassy that take you through check points to the actual embassy. Before you board the bus, is when they check your reason for visiting embassy. For being a US citizen, they just looked at my passport and let me on bus.
The worst that can happen is they won’t allow you to go to embassy and you have to wait at the bus pick up spot. But if they let you go in then essentially you have a really solid case of why the marriage is valid. Remember the interview is looking at how strong the evidence is for the marriage to have been ongoing. Hence the reason they ask when did the couple physically met last time.
Quite frankly, I think me being at the interview was extremely important. It helped my wife as she was nervous. The interview took 1 min, where they didn’t even care about my wife. They literally called her and asked her to take seat and just asked questions from me about what do I do and how long I have worked and that’s it. We were done in at most 5 mins.