Scrum doesn’t really have a project manager role, though I have seen PMs work effectively in Scrum teams.

The Scrum Master is the servant-leader of the team (usually managed by a department head, not their lateral peers like a PM or PO), removing obstacles and keeping things on track.

The product owner aligns the priorities of the team with the organisational and customer priorities. That, necessarily, includes bringing information to the Board and communicating with stakeholders.

The project manager, if you want to put one in, works with the programme manager to co-ordinate a portfolio of projects, keeping an eye on risks and budgets and ensuring that each Scrum team works effectively with the others and in co-ordination with the wider organisation.

So, while I think a hybrid approach can be useful in a hybrid organisation, it’s worth setting boundaries to avoid stepping on toes in practice.