This is untrue. Web standards need two independent implementations. Google can’t convince any other rendering engine besides their own to implement it.
It doesn't take a single no from Apple to veto it; it takes a single yes from anybody outside of Blink to move it forward. Nobody is doing that.
Here is what Mozilla have to say about WebUSB:
> Because many USB devices are not designed to handle potentially-malicious interactions over the USB protocols and because those devices can have significant effects on the computer they're connected to, we believe that the security risks of exposing USB devices to the Web are too broad to risk exposing users to them or to explain properly to end users to obtain meaningful informed consent. It also poses risks that sites could use USB device identity or data stored on USB devices as tracking identifiers.
— https://mozilla.github.io/standards-positions/#webusb
Until Google can convince anybody outside of Blink to implement it, it is not a standard it’s a Blink-only API.