I think the answer is simply that Google is massive and sometimes competes with itself. Android’s Instant Apps, announced a few years ago (seemingly to go nowhere?) seemed like a direct attack on the use case for web sites, but the company tolerated it.
As a whole I think Google wants to chase ubiquity. A PWA will work on laptops, phones, Windows, Mac, Android... an Android app won’t. So they’ll push PWAs.
I too thought of just blaming it on Google's idiosyncrasy, but PWA has stood the test of time with multiple parties (browsers) extending their support.
Perhaps, I'm thinking other way round; May be PWA was supposed to kill traditional web apps and was intended to bring web apps to Playstore/Appstore but it didn't happen(yet).
>Android’s Instant Apps, announced a few years ago (seemingly to go nowhere?) seemed like a direct attack on the use case for web sites, but the company tolerated it.
I think android instant apps are meant for Google Assistant ecosystem, Google Smart Display have it and Fuchsia would have GA; so instant apps might come handy.
They have made it unusually difficult to get it bundled up for the Play store. I mean, it should be as simple as proving ownership and supplying the manifest URL. I think solving the distribution problem would definitely be key to having developers think about it as an alternative to native apps.
As a whole I think Google wants to chase ubiquity. A PWA will work on laptops, phones, Windows, Mac, Android... an Android app won’t. So they’ll push PWAs.