Going with #HoloISO doesn't seem like it would make much sense to me. As far as I understand it is something like an unauthorized derivative of #SteamOS so you'd be putting yourself at Valve's whims without Valve okaying it and no voice at all in the development process.
I like getting the dev team of an open distro involved, I guess #ChimeraOS might have been better if they fit that description as well though.
ChimeraOS is basically a totally hardware-agnostic version of SteamOS, though instead of forking SteamOS it's more like a re-implementation of it from an Arch base.