Azure Migrate now supports Azure Government as a migration project location. This means that you can store your discovered metadata in an Azure Government region (US Gov Virginia).
In addition to Azure Government, Azure Migrate supports storing the metadata in United States and Europe geographies. Support for other Azure geographies is planned for the future.
Note that the project geography does not restrict you from planning your migration for a different target location. Azure Migrate supports more than 30 regions as assessment target locations. The project geography is only used to store the discovered VM metadata.