While the server side is still growing and obviously not as huge as Java etc., Dart definitely is being used on the backend. For instance, https://pub.dev/ itself is written in Dart: https://github.com/dart-lang/pub-dev . :)

The language, like any other, does have some weaker parts, but in general is _very_ nice to write in - thanks to both the language itself and the toolchain built around it.

The apps compile to native binaries for production and are run in Dart VM during development. The SDK is multi purpose. You can write "scripts", you can write CLI apps, servers and with Flutter - the rest of them.

I have user Dart for small personal projects and it's a great language. Somewhat similar to Kotlin, but IMO a bit nicer. Unfortunately the ecosystem is not as developed outside of Flutter as with more popular languages, but it very much exists and pretty nice to use.

Try out serverpod. Not affiliated with them- it's just a super nice integrated Dart backend:

https://serverpod.dev/

I've been using Dart and Flutter for years, but I've never ever met anyone who's seriously using Dart for backend. That would be a very niche thing and not popular with teams.