"There are dozens of us" but seriously, there is some interest from users but most projects done by companies have been abandoned, SwiftUI feels almost like a language divergence, which is frustrating. I'll list what I know about but it's by no means comprehensive.

The good news is that server side on Linux is still working well, Vapor 4 is solid, growing and looks like it has a bright future and Perfect is still going too, though Perfect seems disjointed from the main community. IBM's Kitura and involvement with Swift is over though. Server side seems like it's best future right now, since it's more performant than Javascript and uses less cycles, which can have a lot of cost benefits.

Static site generation looks good too, Publish by John Sundell being the most famous (https://github.com/JohnSundell/Publish) but a lot of others have started springing up lately.

"Swift for Tensorflow" by Google has been shut down. Though that was mostly Google giving advice on how to evolve Swift to work better for ML. It's a shame too, since it felt like Fast.Ai was adopting it and starting to teach it at one point, so the shutdown felt a bit premature, but this is Google after all, shutting things down is what they do.

Swift 5.0+ seems to have stabilized the language quite a bit too(ABI Stability and other things), which is a good thing, as hopefully the tutorials/docs from now on should remain more consistent. The built in package manager "Swift Package Manager" seems to be working better too, though there are still a lot of complaints/missing features, but on the whole I like it.

Swift on Linux seems to be officially supported by more flavors of Linux than it used to be. Meanwhile Swift on Windows works right now but I wouldn't use it in production yet, it throws errors that are the sort that if you ask anyone they will answer "that's normal, ignore that". Some have even gotten modern Swift to run on older MacOS's leveraging LLVM.

Swift WASM seems to have had a big update with Swift 5.4 https://forums.swift.org/t/swiftwasm-5-4-0-has-been-released... though I've not yet tried it having given up on Swift WASM about a year ago.

Youtuber Stega's Gate(https://www.youtube.com/channel/UCBXFkK2B4w9856wBJfCGufg) is building a cross platform game engine in swift.

IntelliJ has a decent alternative to Xcode now too, using Clion with an app made by them(though it's still not as integrated as Xcode, nothing would be).

Getting it to run on android is technically possible, but the workaround it too much, but that's mostly on Google actually, since the support for writing things in C for Android is so depreciated it's a joke.

The Docs are still terrible though, have been to my knowledge since 3.0 became outdated. That said the official books are alright and there are tutorial communities that are pretty good too, but it's shameful that the docs should be that useless.

So yeah, Swift is nearly viable for non Mac things, but there aren't much for libraries outside of backend. Some are tinkering and making cool stuff, but at times it's difficult when even the non app related programming tutorials for those are like "let's do it on MacOS using Xcode".All of that said, it's my favorite language, I want it to have a community similar to Rust's but I don't think Apple supports it the right way for that happen, they seem ok with it staying inside their ecosystem, like they are ok if the community does stuff outside of it, but they aren't helping it or encouraging it, is the general feeling. Ironically I was recommended to Swift initially because of the community that it had at the time, the caveat being "if you want to make apps for Apple's ecosystem", which isn't terrible, but it's not what I want. I'll probably give up on it if it doesn't change in the next year or so and go all in on Rust is likely what will happen, but again it's a shame.