Confirmed. PowerApps landed about 45 minutes ago for our GCC tenant. Initially I had trouble with sign in on mobile app. I kept inputting credentials and getting redirected to signup for Trial plan experience. Then I noticed a small gear in the lower right of the IOS screen. After selecting "Enable GCC mode" everything worked as expected.
Yes I can. I am able to create a connection using CDS, but when I try to use it as a Data Source within PowerBI I get an error.
The environment 'Default-3a573c9f-610e-4237-9520-c8291dad5888' is not linked to a new CDS 2.0 instance. The operation 'ListInstanceMetadata' is forbidden for unlinked environments.
Session ID: ad95240f-ee62-423e-b366-1bfc18bda29f
Regarding the Dynamics 365 Connector, I found an article that says it is not available for the GCC.
I am able to see and use the Dynamics 365 Connector in our non-GCC PowerApps and Flow environment.