Most programs that I've used, after installing them, the installer has a "Run this app when you close the installer" button. Is there a way to make the installer that get's created have such a check box or feature?
Xamarin.Mac calls productbuild for you to generate the package in question (you can see this if you read the build output).
There are a number of answers on StackOverflow that suggest arguments that may give the effect you desire:
You can add those in Project Options -> Mac Build -> Additional arguments under packaging.
Xamarin Inc., as a wholly-owned Microsoft subsidiary acting as a separate legal entity, adheres to the Microsoft Privacy Statement: Privacy & cookies