Deputy Product Owners
"The Product Owner is one person, not a committee. The Product Owner may represent the desires of a committee in the Product Backlog, but those wanting to change a Product Backlog item’s priority must address the Product Owner." - The Scrum Guide
There are a lot of ways in which my approach to Scrum differs from what's in the official guide, and since that document refers to Scrum as 'immutable,' let's just call what I do 'Notscrum™.' In Scrum, there is only one product owner per team. That person is the sole person responsible for the product backlog, and the person who advocates for the work to be done. In Notscrum there is one product owner, but there can be multiple deputy product owners. Here's how it works.
When my program at Viacom was first forming I met with the then-director of the Library & Archive group and learned that while he set the priorities on work done, the archivists were organized in three distinct areas with a team lead for each. Since that was the case, the director became the product owner, and the team leads the deputy product owners. The director set the 'big picture' goals and objectives, while the deputies took a more direct role in managing the backlog and working out priorities with the team. The product owner still reviewed the backlog and approved or adjusted what the deputies proposed, and the deputies were in the planning meetings discussing what was feasible with the teams. The deputies had real authority, although it was delegated. This worked well because, while the product owner paid attention to detail, he was not a micromanager. Further, the deputies weren't hampered by their status, like Barney Fife and his one bullet.
Conditions have to be just right for a team to have deputy product owners. I have a team just now that will begin practicing this approach, with senior engineers taking responsibility for their areas within the work of an infrastructure team. If it works at well as it did with the archivists, then great! If not, well then that's part of inspection and adaptation, which is core to the Agile mindset.