And will it work? Shimano.

No, although some of them you can replace the freehub body to make it work (hope pro2 40t for example)

Even if it did fit, what would the advantage be? I’m assuming they only come in small range 11-28 or something similar.

They do a 11-32, and with the new 11 speed xt cassetes having only 11-40 or 11-42 options I can see a lot of people using them.

I think they will fit, but haven’t tried it.

It’s for a disc equipped Cross bike on which I’d like to install R685 Hydro STIs. They’re 11 speed like the rest of the groupset will be, but I’d like to retain use of CK ISO disc hubs rather than using the weaker R45 Disc hubs.