Smart home hubs are not always needed in order to use smart home devices however, some manufacturers do require connection to a central smart home hub in order to function.  Please note that all products requiring a seperate hub are highlighted in iO-WE.com descriptions

Some brands offer a choice, such as Philips Hue indoor smart home range.  Their indoor smart light bulbs work without the hub but through an app on a phone or tablet. However, add a Philips Hue hub, and you can expand what you can do and how much control you have over your philips hue devices massively.

Here you will find the smart home hubs you might want or for some brands', need.