Setup Stack Entitlement with AWS Cognito?

At this time, the entitlements capability is limited to users from SAML federation (either via the Stacks application entitlements feature, or the Dynamic Application Framework (which additionally requires the streaming instances be joined to a Microsoft Active Directory domain)). You can learn more here: https://docs.aws.amazon.com/appstream2/latest/developerguide/manage-application-entitlements.html.

Instead, you will need to ensure the image only has the software visible that a user should be able to launch. An alternative would be to essentially have your own application that launches the other applications. You could then use session context to pass to the streaming instance which applications should be able to launch, and automatically launch your launcher app. Then your launcher app would parse session context and show users what they need.