Look at how Google pushed Chrome on its websites and people picked it up.

They could do the same for web apps. What's been limiting them all this time is Apple policy.

Apple policy 1- PWAs on iPhone must use Safari, Safari only has features Apple chooses to implement

Apple policy 2- Add to Home Screen is hidden away

Now with DMA, Google could make its own web browser, provide all their apps as "PWAs that work with Chrome and not Safari" and people could go along with it. Heck they could even start their own app store without the apps having to follow any of Apple's "alternative distribution" rules- because they're web apps, not native apps.