> exactly a result of Apple wanting to prevent app distribution channels other than their App Store
Nah, it's because PWAs were a standard created by Google, with Google being the primary market driver, solely with the interest of advancing Google's own interests (both in undermining Apple, and making lower-end devices more usable in developing markets). Don't think Google invented PWAs, or heavily pushed them, out of some charity. Notice also that as the ultra-cheap phones (~$100) have become more powerful, and as Apple refused to take the bait, that Google's efforts behind PWA have mostly ended.
The same goes for RCS, even though it was initially made by a neutral vendor forum. Google became the heavy pusher of RCS, not just for the sake of Android, but because they had carrier deals to use Google's own infrastructure (Jibe) for RCS, and forcing Apple to accept and integrate with their own infrastructure is a better position to be in.
This is also, let's be clear, not the first time that Google has tried an "open" standard to advance their interests and bludgeon competition. AMP is what happens when the standard catastrophically fails.