VP9/WEBM with Chrome for IOS
Solution 1:
https://stackoverflow.com/questions/39790639/webrtc-support-on-chrome-browser-in-iphone-ipad
According to this post, the answer is no. Because Apple don't allow Apps in their store that implement their own web rendering engines (aka browsers). Therefore every 'browser' currently available on the App store is just a skin on top of the built-in web render, which explicitly doesn't implement VP9 / webm support.