I don't think there is a limit to how many apps icons can be in an iOS folder, they're paginated. Right now, I have 27 in an "Apple" folder, spread over 3 pages. If I add another icon, it adds another page.
It could, but I won't hold my breath. I've fallen into the trap of being optimistic that some annoyance will be fixed or some obvious improvement will be implemented in iOS <next_version> multiple times and ending up disappointed. I'm even less hopeful of anything that would improve PWAs, whether in terms of API support or user experience, due to Apple's incentive to keep them second-class.