Being backed by Google was huge. Swift is backed by Apple but not outside of their specific use cases. If Apple had announced they were going to start making all their backend services in Swift too I imagine things could have looked very different.
* linux, windows and wasm compilation targets. They hired the maintainer of wasm project as well.
* LSP language server for Swift, to power VSCode and others editors, even though, they use Xcode that doesn't need it
* well tested server side libraries similar to netty/jetty (they even have a former Akka developer)
