[southerntofu]

There is definitely many Chrome-only features. Vendor prefixing before standardization is quite common in CSS land. And each browser makes a choice whether to implement certain JS APIs.

Moreover, Chrome is pushing many new APIs faster than any other vendors can implement. Due to governance changes over the past 20 years at W3C, Google and other user-hostile industry behemoths now more or less control W3C and can push many new specs to be "standardized". But not all APIs are created equal: for example Firefox dropped Battery API support because its only usecase was user tracking, so you can essentially say Battery API is Chrome-only despite being being a standard.

Also, although slightly unrelated, as a long-time Firefox user, i know that for some obscure reasons some websites don't work in Firefox, and that Google apps sites are known to act slower when presented with a Firefox user agent. I'm also old enough to remember that when Chrome came out (oh, i miss you pre-Chrome web) Google *paid* website operators to include Chrome advertisement and to make their demos only work via Chrome (once again, via user-agent filtering not via actual features of Chrome that would not be available on other browsers).