- can WebRTC DataChannels / multiplayer operate on mobile?
Yes. However some cell data providers have restrictive network address translation (NAT) that can block peer-to-peer connections. (That won't affect wifi which uses a different connection.) You'd need to run a TURN server to reach ~100% connectivity anyway.
[quote:1pitrj1v]If safari supports it, would it work when wrapped with Cordova?
Yes, WebRTC also works in Cordova when it's supported.
[quote:1pitrj1v]- is WebRTC is on how many browsers now in 2018?
Chrome, Firefox and Safari 11+ all support it. Safari has a bug that can cause connections to drop that is already fixed, just need to wait for the 11.1 release. The only browser with no Datachannels support is Edge.
[quote:1pitrj1v]could a game using WebRTC work on a site like Kongregate?
Yep, nothing special about that case, WebRTC still works.