I have not tried out voyager, but just from looking at it's GitHub, it's essentially just a web browser packed in a native app anyways.
Performance shouldn't really be different from browser app to local app this way unless something is done wrong, or there's some specific functionality, like async I/o that's still unsupported.
Notifications are also a thing in web browsers nowadays. Most device features that you can access in a separate app are actually supported by now.
Nah, Voyager is primarily a pwa that works entirely in your phone's browser.
They recently packaged it with a browser into an APK because lots of users asked for a "native app" for some reason. But the pwa is still there, and is still the main way it is developed
But no front end for Lemmy should ever need to be an app.
Because not everybody likes the stock interface of Lemmy. Same thing with Reddit, and why people chose to use third-party apps there, as well. Web apps aren't always designed in the most intuitive ways for every user, and sometimes a native app can fill those UI/UX gaps, or add features that aren't possible through a PWA.
why PWA and not a plain web app? I think the only difference is that PWAs can ve turned into a pinned pop-up window (that acts a bit like an electron app) when using a chromium-based browser.
Even then, there's a lot of feature you end up missing out on. Even just basic navigation has to be done via the browser's default navigation options. Even simple things like long-pressing something on the page will typically only give you access to your browser's long-press menu (though that's not always the case, in my experience very few web apps handle this effectively).
Personally, I prefer the experience of a native app. But I get why it's not appealing to all people.