Prepare the PKG for Proper Installation (Key Step from Official Docs):
Copy the .pkg file from your publish folder (e.g., bin/Release/net8.0-maccatalyst/publish/) to a neutral location outside your project, like the Desktop.
In your project folder, delete the entire bin and obj folders. This removes any linked .app artifacts that could confuse the installer.
Double-click the copied .pkg to run the installer. It should now place the app in /Applications.