As mentioned by others, the G.Fast pod always goes on the PCP.
What you pictured is an expansion to the Fibre cabinet, known as a High Density expansion.
It adds space for more ports (i.e more customers).
This image of Ignitionnets cabinet is a great example of a G.Fast pod.
The G.Fast pod on the left has vents.
The unvented part on the right is just a PCP extension to hold more tie cables.They are usually added at the same time as a 2nd Fibre cabinet.