The Microsoft example seems a bit desperate - they bombed in mobile so of course they're seeking cross-platform refuge.
But are PWAs being used that much for real? Beyond just installable web sites (ie. full offline support with service workers, etc?). I seem to remember Twitter did a nice job with Twitter Lite, but I've never seen anyone use it. Again from memory I think Skype did a quite impressive PWA. I'm a big fan of Checkvist, & they have a PWA which is moving slowly but in a good direction.
Anyway, that aside, for a dev wanting to get into the mobile space (which I think was the OP's intent), PWAs would hardly be the best first option for a tech to learn. Surely whatever your personal tastes, you wouldn't disagree?
Yes, many digital web agencies are going through that route for mobile web sites, instead of having to deal with native toolchains.
Do you also consider Google and Apple's move desperate then?
While Microsoft has definitively bombed on phones, they are doing pretty alright on convertible laptops/hybrid tablets.
As for best option, I also mentioned a couple of other ones, which I advocate as alternative to PWAs.
I see Flutter has a future as bright as CoffeeScript, if it keeps being tied to Dart.
As for React Native, it depends on how much one feels like having to deal with JavaScript and the interoperability issue that often happen across Android devices.
It was your invocation of Microsoft's move I considered desperate.
You're still studiously avoid mentioning any actual PWAs. I'm someone who wishes PWAs would take over, as I dislike all the OSs and don't want my usage habits or data to be tied to them. But as of now it's not happening, is it?
If a person was trying to advise a developer new to mobile apps, with their interests rather than the advisor's tastes in mind, I cannot believe they'd advise PWAs as a primary focus.
Learning a platform isn't a forever-decision. A new mobile app developer can always learn new tech as needed. But if they want a start now, they're better off learning what's dominating today.
Because the ones I am fully aware as PWAs, are the projects I worked on for internal enterprise customers, not something that joe and jane get on their devices.
EDIT: besides the examples posted by lucasverra, you have KaiOS with its relatively big Asian market share, Google Go-Apps variants of their apps are mostly PWAs.
I know there are some decent individual examples (indeed I mentioned some myself). I'm just unconvinced that the once-anticipated shift from native apps to PWAs is happening. They are expanding into some niches, but mobile app development is still overwhelmingly native. Certainly for my local job market, only an ideologue, uninterested in the repercussions of their advice, would suggest to a mobile app newbie that they learn PWA tech first - iOS & Android developers will walk into a job anywhere, whereas they'd be hawking for a while to find work building PWAs (though web tech more generally is hot as always of course).
That is the whole point, 90% of mobile apps are actually CRUD apps that can be easily done as mobile Web SPAs.
The PWA part is just yet another tool on mobile Web.
Also in case you missed, I suggested Qt, Xamarin and C++ with Native views.
As for job market, on my area you would be having an hard time finding 100% pure native development offers, everyone only cares for some kind of solution that can be deployed across Android and iOS.
But are PWAs being used that much for real? Beyond just installable web sites (ie. full offline support with service workers, etc?). I seem to remember Twitter did a nice job with Twitter Lite, but I've never seen anyone use it. Again from memory I think Skype did a quite impressive PWA. I'm a big fan of Checkvist, & they have a PWA which is moving slowly but in a good direction.
Anyway, that aside, for a dev wanting to get into the mobile space (which I think was the OP's intent), PWAs would hardly be the best first option for a tech to learn. Surely whatever your personal tastes, you wouldn't disagree?