This extension is for "pure" Swift development, not iOS development. I doubt the latter will ever officially happen. It's possible to make it work for iOS at an unofficial capacity though by hooking into the extension's LSP support. We did this at Spotify to enable iOS development in Cursor for Bazel iOS projects: https://github.com/spotify/sourcekit-bazel-bsp
What's the point then? Because nobody use Swift outside of iOS app development.
You also can't do Android (app) development outside Android Studio.