Is integrated apps page available in Microsoft 365 admin center of GCC high environment?

Question

Hello,

We have developed an outlook add-in hosted in Microsoft 365 commercial. We deploy/publish the app using Integrated apps page from M365 admin center as seen in the screenshot below. We use the XML file uploading method.

I wanted to know if the outlook add-in is available in M365 GCC High environment. I connected with the client who are using Microsoft 365 GCC High and their Global/Tenant IT Admin is unable to access the Integrated apps page. So would like to know if outlook add-ins are available on GCC High and if there is difference in the way we publish the apps.

Thank you!