Scrum improvement

Deploy frequently and asses how the users and market react :-)

What about the development team in scrum?

How is productivity being measured in Scrum? What should the main purpose and outcome of a Sprint be? Does it make sense to measure the productivity of the Development team only?

Aleksandar, why are you focused on measuring Development Team productivity increases?   How do such increases translate to customer satisfaction?   Are you just creating more stuff, but not the right stuff?   Are you delivering more stuff, but assuming more technical debt in the process?   How is the team doing reducing/eliminating silos and handoffs?   How well does the business identify the most critical items to work on?

Scrum Maturity and growth can be assessed in many different ways.   Development Team productivity is probably one of the least valuable metrics for this.

You could read the question differently, in the sense of how would a Scrum Team best measure productivity.

That would involve having a Product Owner who can clearly articulate what product value is expected to be, a Development Team which can deliver increments accordingly, within a collaborative Scrum Team which can inspect and adapt its progress.