thanks for the question!
xamarin-archive step builds your xamarin solution it calls two type of build commands: the first builds the solution to build shared resources and dependencies etc… , then it calls the platform specific build commands which generates the platform artifact (.ipa, .apk, etc…) files.
Specify project types to build input of the step, you can control which platform specific commands should run and which not, but it does not have effect to the first build command against the solution file.
If you want to fully avoid building one platform’s project, please create a solution config+platform in your solution, which only maps to the projects which you want to build.
In this sample:
Release configuration +
Any CPU platform maps to every projects.
But in this example:
the same solution configuration + platform combination does not builds the Multiplatform.Droid project.