Google has actively developed an entire UI framework for mobile applications that compiles directly into HTML+WASM. They want the browser to be competent, because a competent browser can attract money iOS users would otherwise spend on App Store fees.

I don't see how it would be "relatively straightforward" to make web browsers competitive if Chrome barely manages to keep up. There's a _lot_ of money going into making Chrome an alternative to the Android/iOS/macOS/Windows SDK, to the point where modern GUI applications have thrown out native controls and just render everything to a browser window instead.