Hello @eg1995
You are correct, first you need to transfer an Azure subscription to a different Azure AD directory(Tenant) and then move the resources to different region.
- Transfer an Azure subscription to a different Azure AD directory(Tenant). Be aware that not all of the resources can be transferred between Tenants
https://learn.microsoft.com/en-us/azure/role-based-access-control/transfer-subscription
- Move the resources to different region.
https://learn.microsoft.com/en-us/azure/resource-mover/move-region-within-resource-group
Azure DevOps migration to another Tenant
- Change your organization connection to a different Azure AD by switching Directory in Azure DevOps settings
https://learn.microsoft.com/en-us/azure/devops/organizations/accounts/change-azure-ad-connection?view=azure-devops