"normally" is carrying a lot of water there. While the back-end is shared, obviously, a large number of orgs have two distinct fully native development projects for the platforms. There are zero empirical metrics I can cite, but in my experience the cross platform thing is a minority. Cross platform tooling is often the talk among the aspirational "One day I'm going to write a novel, and then a hit app" sorts, but it just doesn't dominate in the actual industry.
But if it did, Flutter dominates the cross-platform world, and what do you know, Flutter can generate PWA apps.
>But even aside from Apple's lack of support
Apple has supported PWA for a couple of years. It was a lazy excuse by cheerleaders who had nothing factual, but Apple supporting PWAs didn't move the needle at all. Because it turns out that a billion Android devices not being targeted with PWAs had literally nothing to do with Apple.