Apparatus and method for servicing data transfer commands in a computer environment using a selected protocol such as NVMe (Non-Volatile Memory Express). In some embodiments, a secure connection is established between a client device and a bridge device across an interface. A controller of the bridge device presents a unitary namespace as an available memory space to the client device. The controller further communicates with a plurality of downstream target devices to allocate individual namespaces within main memory stores of each of the target devices to form a consolidated namespace to support the unitary namespace presented to the controller. In this way, the bridge device can operate as an NVMe controller with respect to the client device for the unitary namespace, and as a virtual client device to each of the target devices which operate as embedded NVMe controllers for the individual namespaces.