Cross-tenant work in GCC High depends on Entra External ID cross-tenant access, Microsoft cloud settings for cross-cloud collaboration, and label configuration that lets invited B2B users open protected content.
Microsoft Defender for Cloud Apps in GCC High gives security teams discovery, control, and monitoring for third-party SaaS that affects CUI programs, with government cloud specifics and documented App Governance gaps.
FedRAMP authorization or equivalency for a cloud service does not create CMMC reciprocity for a contractor, but the FedRAMP body of evidence can support CMMC Level 2 assessments when you scope it and map it to NIST SP 800-171 objectives.
Microsoft prices and packages GCC High differently from commercial tenants, and those differences drive spend, capability, and timing decisions for DIB organizations that handle CUI and export-controlled data.