At what level in the Google Ads interface does the marketer select Android or iOS as the mobile app platform?

The mobile app platform (Android or iOS) is selected at the campaign level in Google Ads. When creating an App campaign, you define the target operating system during the initial campaign setup. This allows Google Ads to optimize ad delivery and targeting specifically for users on the chosen platform. The reporting level is for viewing data, not making targeting selections. The ad group level is for organizing ads and keywords/audiences within a campaign, but the platform choice is broader and applies to the entire campaign. The asset level refers to the individual creative components (images, videos, text) within an ad, not the platform targeting.