Chrome and Firefox are building iOS browsers that do not require the apple WebKit. Everyone, including apple, expect apple to drop that requirement soon to help avoid antitrust issues.
Definitely not Android. Firefox is unfortunately quite a bit slower than Chrome based browsers. I still use it as I don't really do much on my phone, but I hope they can optimize it further.
I think for now it's on desktop Windows? But on Linux I do notice faster react app load like reddit new design is faster. But I use lemmy, so it doesn't matter now.