I think that’s not true for EU devices? Not sure if there are any browsers with an alternative engine are actually available though.
https://developer.apple.com/support/alternative-browser-engi...
https://developer.apple.com/support/alternative-browser-engi...
However, no browser engine has bothered so far because they'd need to upload a separate app to the app store specifically for EU users, and non-EU developers cannot debug the application on a real device so manpower is region-restricted unless you hack around the limitations.
The browser is called Ladybird and it isn’t Apple’s test suite, web-platform-tests is a collective effort all the major players contribute to. Almost two thousand people have contributed to it:
https://github.com/web-platform-tests/wpt/graphs/contributor...