How to deploy a AVD managed service to a Client and use the Client Azure AD in another tenancy

Managed Service ISV solutions in Azure  want to secure AVD and their applications in a managed tenancy but the end Client wants to use their identity which is in the Client tenancy. In most cases their is also a Client on premise domian and an AD connect directory sync.

How can we deploy the AVD solution in a separate tenancy and use the Client users profiles to log onto AVD.

Thanks Mike