Is it plausible that the libraries are so big? I mean, for example, NodeJS is in the order of 100mb and contains the whole v8 engine.
The Gmail app size has to be assets, right?
You'd be surprised what ends up dragged into where when you have a build system that makes it easy. Just look at the npm.js mess (and what kind of things ended up depending on what kind of other thing) if you want an example.
Static linking will do that. Imagine you have 400mb of binary objects your app depends on. Libraries your company uses for app analytics, SSO, 2FA, Corporate service bus api, etc. You statically link all those for your 50mb Swift UI app and bam, you’re in the 700mb range.