Is there an Interoperable WiFi Mobile Peer to Peer Solution

Is there an interoperable WiFi Mobile Peer to Peer solution? Apple has Multipeer Connection. Android and Windows has WiFi direct. The two P2P methods are not interoperable. In other words, An iPhone cannot connect to Android. There appear to be some proprietary solutions that are interoperable. However, I think they are using Bluetooth which is a lot more interoperable. Anybody know of a WiFi P2P solution that connects an iPhone to an Android phone?