How can an organisation ensure applications are only installed from known trusted sources?

Disallowing unknown sources via policy using an EMM (Enterprise Mobility Management) is the most effective and scalable way for an organization to ensure applications are only installed from trusted sources. This policy prevents users from sideloading apps from outside the Google Play Store or other approved app stores. While Google Play Protect offers scanning for malicious apps, it doesn't prevent installation from unknown sources. Informing employees is a good practice but relies on user compliance and isn't a technical enforcement. Specifying a device unlock or work profile security challenge enhances device security but doesn't directly control app installation sources.