At this pace it would likely take decades just for them to be complete enough to show up on MDN or wpt.fyi
But I agree. With Microsoft ditching their independent Edge and becoming Chromium-based and Opera doing the same we're really down to 3 real engines. The best fourth option we can get are Goanna-based browsers like Pale Moon which are themselves just an early fork of firefox
A completely new and fresh often can go a long way in safeguarding the openness of the web. Even if there's not a powerful company behind it