It's 1 and 2:

A software app that runs on a PC, Mac, tablet (Android/iOS), or phone (Android/iOS), acts as a server (PC and Mac for the time being) or a client and/or remote to a server (all devices), can stream via ethernet to any Meridian Sooloos endpoint, and to USB devices (inc. Explorer, Director, Prime) connected to PC and Mac clients. Any device can be made to control any zone, unless you configure a zone as "private" to a device.

Not everything will be available at launch (e.g. phone support, I believe), but the PC and Mac stuff will be.

Roon Developer and ex-moderator of this Forum
I am #25 in the HH1 photo of fame.