That’s why I was wondering. The Guide clearly says PO = 1 person. But I’m wondering, even though they retain the authoritative voice, could others pitch in a do a lot of work that the PO retains authority over.

In a couple coaching assignments I have had, some SMs asked me to do a (non-certified) SM training for their whole team. At the end, when they got back with the SM, the SM asked who might want to try organizing and facilitating the ceremonies (on a rotating basis). One team had each Retrospective facilitated by a different team member, for example. The SMs were still present, but just as support for the team member facilitating the particular ceremony.