While poking around a second-hand store I saw four Switchbot Curtain robots (U-Rail) going for $55ea, with the optional solar panel included for each.  They look to be in good condition, nearly new.  I've been toying with the idea of making my curtains smart, but I'm not sure if these will work.  From what I can work out online, U-Rails mean that the track looks like an inverted U.  However, my curtain tracks are predominantly C-shaped - the curtain hooks go into the eyelets which run along the track through the gap in the back of the rail.  Would the U-Rail robots work with this C-shaped track?

These units don't appear to come with a hub.  Would they work OOTB with home assistant, or would I need to also find a hub for it?  Or could I just pair it with Alexa for voice control?

Finally, would I need two units for a pair of curtains?  I suspect so, as the box doesn't look large enough for a pair of the devices.