This is certainly way less user-friendly in 3.8 than it was in 3.6!
Thanks for the info above it really helped me. A few more specifics if anyone needs them, the exact command I found to work is…
dotnet publish --runtime osx-x64 -c Release -o Publish -p:PublishSingleFile=true
…when run from the project directory this creates a single file built from the ‘Release’ configuration and output to the directory called ‘Publish’.
Double-clicking on the resultant file did nothing until I renamed it with a ‘.app’ extension. I can’t see a way to do this from the command line, it just seems to use the project name for the name of the file.
Once renamed the file can be launched though for some reason it now has a duplicate extension of ‘.App.app’, though this can be renamed again.
The file is seen by the OS as a ‘unix executable’. It is not the normal app ‘package’ I’d expect on MacOS so I have no idea whether this can be uploaded to the AppStore (I doubt it) or even distributed via Steam as there’s no info.plist, icon bundle and all the other things you’d expect.
If anyone knows how to turn this into something that resembles a ‘proper’ Mac application I’d be all ears!