Web apps can't fully replace native apps. This would be a bandaid fix, we need a fully open ecosystem for apps, like what is available on PCs. Native apps can run offline, they can be much more deeply integrated into the OS (you can't have a web app Android launcher, for instance), and they have a performance overhead due to having more layers between them and the hardware, which is important for games or anything complex.
I have high hopes for the Rust UI ecosystem in this regard. It's implementing pretty much everything from scratch, which means that it should be able to support a standalone GUI ecosystem that doesn't depend on a system GUI toolkit being available (while also being able to target existing OS's).
Web apps can run offline. Google could figure out web app android launchers if they wanted to. The performance overhead exists but is slight. It doesn't matter to 90+% of applications, including many games.