Earlier quoted context omitted.
Fortunately you don't need everyone to be on iOS to reply. So you can send your Android using friends invited and they'll just get a weblink.
Unfortunately you need an iPhone to create the invite, or contribute anything else than a reply. They have to know their uncoolness is tolerated but not welcomed in the walled garden.
You can say the same thing about FB/Whatsapp or any other social network - you have to be in-network to get the invite even.
Looking forward to testing this out for some events.