Here's a thought: what about identifying certain sprints as a miletone sprint. It's a sprint that when it delivers its increment, the overall delivered product has reached an important milestone.
The milestone can be that the project has reached an MVP stage which can be delivered and used by the users, or whatever milestone has been agreed.
Sprints are all meant to ‘deliver business value', but realistically most of them just showcase the increment. Their increment is often still unusable, and no change to the surrounding organisation has occurred.