As the other person said, Edge is Chrome. This may sound like we're just being obtuse, but the point is that this 'standard' may only be a standard on paper so far.

Google may have (half-)written and implemented the specification, without going the full way in the standardization effort, which is to say, talk to Apple & Mozilla:

• whether they actually want to implement it. Even if OP thinks, it's the coolest feature in the world, it means real implementation+maintenance work for Apple & Mozilla, which they might simply not be able to afford.
• if it needs to be specified in a certain way to help Apple & Mozilla implement it. Evidently, Google didn't specify it in whole from the start either, which may very well reflect on what was easy to implement for them.