Can I restrict access to a specific app inside a Firebase project?

I have a Firebase project that contains multiple iOS apps, each for a different customer. This is great for me to be able to view analytics across all of the apps, but I want to give each customer access to the analytics specific to their app. I see that I can create a new user and assign them the Firebase Analytics Viewer role which limits them to only analytics. The problem is that the user can then see analytics for all apps in the project.

Is it possible to restrict access so that a given user can only see analytics for a specific app?

You can build comparison in google analytics analytics.google.com and provide access to specific reports to specific users. How custom reports are built and shared can be found here.

You can build reports by specific app by using Stream ID filter which can help you build reports on per app basis.