Good luck getting all the developers to rewrite their apps. The only reason you had any apps was because it was based on Android so it was little to no effort to port. Going plain ol' embedded Linux is basically the death knell of your developer story. Source: been there, had no third party apps, switched to Android
Oh man PWA as a replace to traditional apps have been promised for a while.
On one hand the promise of write once run anywhere on the other less ability to lock down your app from your users (good for us, but not popular in the mobile space at the moment)
You’re likely thinking KaiOS. They are still contributing what is required under MPL-2.0 but the rest is proprietary. KaiOS 3.x finally got off of a browser from 2016 as the base, but very few have upgraded their apps to be compatible (the tweaks were minor) & others have used it as a reminder that they were still ‘supporting’ a platform like whoever is maintaining or using that WhatsApp thing for chat.
There’s also Capyloon built from B2G, but it’s still early on & is targeting touch phones, instead of feature phones.
It would be nice to see it around IMO since it’d just be another enhancement to progressive web applications & JavaScript is a better target than Java or Swift.
PWAs are great if they're written well, especially if they allow offline access.
There's platforms like React Native where the apps are native on each platform (they use native UI widgets). You can't just run the same code, but you can reuse probably 90-95% of code across platforms.