You link to https://web.dev/learn/pwa/capabilities and https://whatpwacando.today elsewhere, but I think many would consider many of those features to not be inherently PWA features. Many, _many_, of those features have wide usage outside of PWAs, which makes putting them into a "PWA" bucket somewhat meaningless. Constructing buckets like "Storage" or "Media" would probably be more meaningful to web developers.
If you look at the basic definition of PWAs, it's primarily about manifests and service workers, and about using the web platform in combination with these.
Manifests are hard to test automatically — their content is largely shown in differing parts of browser UI, and UI is by-and-large unspecified in web standards (because vendors want freedom to make their own UI decisions) — which makes including them difficult. It's also unclear how much there is in way of interoperability problems.
Service workers are definitely something that could be proposed (though haven't been in recent years); I again don't believe there's been that much in way of interoperability problems there recently.