The engine absolutely matters! If you want to use a feature that is available in Chrome and Firefox, but not in webkit/safari, you are completely out of luck on

The engine absolutely matters! If you want to use a feature that is available in Chrome and Firefox, but not in webkit/safari, you are completely out of luck on iOS. Apple has been holding back web development for many years with this policy. I suspect it is to keep PWAs from being competitive with native apps, but whatever the motivation, that is very much the effect.