SwiftNIO is a cross-platform asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. (https://github.com/apple/swift-nio)
Distributed Membership Protocol implementations in Swift: https://github.com/apple/swift-cluster-membership
Docker Official Image packaging for Swift: https://github.com/apple/swift-docker
Also, on official https://swift.org/download all releases and snapshots are automatically available for: Ubuntu 16.04, Ubuntu 18.04, Ubuntu 20.04, CentOS 7, CentOS 8, Amazon Linux 2
Official Swift Server work group is a steering team that promotes the use of Swift for developing and deploying server applications: https://swift.org/server/
Swift AWS Lambda Runtime: https://github.com/swift-server/swift-aws-lambda-runtime
Official Swift 5.3 release goals have stated a major goal of "expanding the number of platforms where Swift is available and supported, notably adding support for Windows and additional Linux distributions." (https://swift.org/blog/5-3-release-process/)
I’m sure being able to share domain specific Swift code between client apps and backend would be pretty high on their list of wants.
Also, little clues like the way Xcode generates SwiftPM packages in a Linux-ready fashion out of the box shows that they care at least a bit.
Having a lot of interest in the programming languages, my opinion is that Swift is a damn good one. It’s very high level, supports FP deep enough, has a great type system (that is getting better with every release), great OOP support, native performance characteristics and it still lets you get to a really low level when you need it.
I also like how they took great ideas from Haskell, Scala, Smalltalk, C# and others. I code daily in Scala and Swift, previously had done Erlang, Clojure, Common LISP, TypeScript, Ruby, Python, Haskell, OCaml, Java, PHP, C, Smalltalk and some others. In this list, Swift is now almost at the top.
They need to get Higher-Kinded Types and then it’s going to win the world (just kidding, JavaScript gets to win the world, unfortunately) :)