You may see the following error:
/home/rich/hello-dotnet/hello-dotnet.csproj : error MSB4057: The target "PublishContainer" does not exist in the project.
That likely means that you are using a .NET SDK version prior to 8.0.200 while trying to publish a non-Web or non-Worker project as a container. In that case, either upgrade to 8.0.200 or add the the Microsoft.NET.Build.Containers package to that project to provide the required PublishContainer MSBuild Target.