We did it last time in Rome. EXPENSIVE - but well worth it. We were in the Vatican and St. Peter's for 90 minutes. There were a total of 24 of us there. That's it - no other people. They gave us the keys to open the doors (it was all pretty ceremonial, but fun) to all of the different areas of the Vatican. HCBW opened the door to St. Peter's Basilica.
https://thevaticanmuseums.com/vatican-tours/vip-early-entrance-vatican-guided-tour/