If you subscribe to the Ubisoft Channel on Luna good news one of the most influential games in Rainbow 6 Siege is now available and it is the Ultimate Edition. Ashes2Ashes confirmed to us that the Luna is cross play with the PC which is great to hear. This is the second game on Luna to feature multiplayer and more is hopefully to follow!
Luna is currently in beta and more invites are going out all the time. It is only available in the US at present and you can apply for the beta here.