TL; DR: The Meta-Retrospective
The Meta-Retrospective is an excellent exercise to foster collaboration within the extended team, create a shared understanding of the big picture, and immediately create valuable action items. It comprises team members of one or several product teams—or a representative from those—and stakeholders. Participants from the stakeholder side are people from the business as well as customers. Meta-Retrospectives are useful both as a regular event, say once a quarter, or after achieving a particular milestone, for example, a specific release of the product.
Read more on how to organize such a Meta-Retrospective and do not forget to check out the free Miro Meta-Retrospective template.