No I don't think that's it either. Home assistant runs on a server somewhere still.
What the top level comment is asking for, completely unrelated to the article mind you, is to have a smart device in the form factor of a light switch that you can hook into your home assistant system.
The problem they likely have (I have it too) is that you set HA up and it can control smart plugs, smart thermostats, etc, but it can't control 99% of the existing lights in your house because they are wired to dumb lightswitches. Instead of some mechanical finger flicking a switch or something, why not uninstall the existing light switch and replace it with a smart one.