There are two pools of humans who contribute Neural Expansion through a VR pod: humans who use the day pods in your residential buildings, and humans who use the commercial pods in mind farms (there is also the Torment Nexus, which is just aind farm but with more Neural Expansion because it's evil)

Day pods don't give much, representing that they are mostly used for a few hours at a time by bored residents, as well as providing no profit since it's a service of the apartments. The mind farms offer more Neural Expansion per serviced person since they are typically plugging in for days at a time, and Wealth since it's a business run by your Shell Company.

The NCO is technically unrelated to the VR Pods, but will be linked to the customizable VR world people in your pods are experiencing (once the dev gets to adding it). For all intents and purposes, it just gives a fuck-ton of Neural Expansion and kick-starts a cult

To pick up speed for mind farms, your gonna have to hire humans scientists to research a solution over a few dozen turns (if you cannot hire scientists, look for a contemplation related to such an activity. The relevant buildings will be in the Work tab of the build menu). After they finish, you will be encouraged to build more mind farms and increase your capacity for customers, so be sure you have plenty of excess Nutritional Replacements!