The "Hub" device can be as simple as a USB stick that's attached to the machine running Home Assistant. That's what I have been running for years, a Z-Wave USB stick that passes through to a ZwaveJS docker container (which also communicates with HA).
So it's not like you need a big stand alone device that has to have it's own Wifi or ethernet or anything like that, it's just a USB stick.
Thanks! This is what I eventually got to. That said, I'm leaning towards putting the USB stick in a Pi or something like that, which is attached to and powered by the router!
Just want to have the one device and I think that's maybe the simplest way to get it without trying to run stuff on the router.
Basically, it is a hub, but it's more of an attachment to the router than anything else.
So it's not like you need a big stand alone device that has to have it's own Wifi or ethernet or anything like that, it's just a USB stick.