There are literally no other metrics. Web Platform Tests were literally a project to align browsers on compatible implementations of a bunch of web APIs. Star

There are literally no other metrics. Web Platform Tests were literally a project to align browsers on compatible implementations of a bunch of web APIs. Started by Opera and w3c and maintained by w3c https://www.bocoup.com/blog/wpt-an-overview-and-history https://www.bocoup.com/blog/wpt-an-overview-and-history