Explain hubs to me

[Ebo100]

I have a number of Alexa devices coupled to some tp-link sockets and Sonos and looking to expand the home automation, currently without a hub anywhere.

We are looking at motorised blinds and have looked at Somfy for an Alexa powered option that I can expand with various sensors but it looks like it needs their own Tahoma hub to control everything. The website has this at around £280 and some of their sensors at £90; which seems excessive when an Echo plus and smarthings hub are much less. So is a hub a hub or are they all unique in the language and/or protocols and would an echo plus be able to control everything?

The website https://shop.somfy.co.uk/smart-home/smart-home-pac...

quotes Integrated protocols: io-homecontrol and RTS but this means nothing to me