How does a Smart Switch that does not require a neutral work?

Whoever you're listening to on this is spouting technobabble

I'm sorry to say, but you probably should find a better source to read, as whoever's been feeding you information is spouting total nonsense. Whether a device needs a neutral wire or not has nothing to do with any sort of IoT contrivance such as a "smart home hub" and everything to do with how the device powers itself. As you have noticed, "smart switches" have electronics inside that need power to run, and they have to provide that power somehow; the same is also true for occupancy sensors, timers, and some, more sophisticated, types of dimmers as well.

However, old-school knob dimmers and plain toggle switches don't need such, and were often wired in a way that doesn't make neutral available at the switch box (the old way of wiring a "switch loop"), meaning that you can't put fancy things there unless they cheat. Some smart-switches are naughty (but UL approved to be a bit naughty due to the low currents involved) and return their supply current through the equipment grounding wire; this means they don't work in old houses without grounding, and also can cause problems downstream of GFCIs.

Others avoid this by returning their supply current via the controlled load (light, fan, or what-have-you) instead; while fan motors and incandescent lightbulbs don't mind having a wee bit of power trickled through them while supposedly "off", this causes LED lightbulbs to play up (either flickering periodically, or simply glowing dimly) as they are much more efficient (read: sensitive) than their incandescent counterparts. It also is problematic if you want to use the smart-switch to provide a control input to another control device, such as a relay, lighting contactor, or dimming power module, that has more "grunt" than the smart-switch, or provides a capability (such as multi-way switching) that the smart-switch doesn't have on its own.

Finally, there are a few wallbox devices that are battery-powered (some Intermatic wallbox timers are this way); this avoids the difficulties listed above, but obviously requires the occasional battery change in order to keep the device up and running. All of this is true no matter what sort of "smarts" (such as wireless capabilities, programming support, or what-have-you) the device has inside it, or whether it has any use for a hub or not.