I think the offline storage situation is improved with the latest manifest structure, although I haven’t experimented in depth. I know that at least one of my PWAs has local data going back a couple years at this point.

I really wish Apple had kept investing more fully in this space. So many of the pieces are there, but like you said, there are still assorted blockers.

It’s clear they still care about this space to a certain extent, since they have been fixing bugs and making improvements (screen-lock APIs and offline support, for example). But it could be so much better.