I am not really clear on your question and do not explicitly use OKR, but OKR and Scrum could be a close fit. Objectives in OKR can be seens as Sprint Goals, and the measurable Key results can be seens as PBI's. On a larger scale, Objectives can be "the product", and the Key Resuts are the sprint Increments, which are in turn measurable. So designing your Scrum implementation around this, you can make this fit yourself.
If you want to learn more about metrics, I can encourage you to read
Actionable Agile Metrics for Predictability (An Introduction) by Daniel Vacanti