Apple doesn't allow 3rd party engines on iOS because if they let web apps get too capable then people will stop paying a 30% premium for App Store apps.
New wake lock api works in safari but when it is added to home screen. Then it fails silently…
Webkit team said that they fixed it 6months ago but Safari team does not accept fix.
They changed their rules a couple years ago to make it pretty much consistent with Apple's policies, but I think some of the bigger players got exceptions.