Get UWP Store associations using PowerShell or MSBuild
I would say probably not, as the Associate App with the Store Wizard, is an authenticated Wizard which requires a users Microsoft Account to be registered with Visual Studio, Load Credentials from storage or asking for OAuth, and then Visual Studio goes to Microsoft's server to Sign the Certificate and Sign the app with it.
AppVeyor documentation says the currently UWP is not officially supported for UWP, as a Microsoft License is required.
Edit: Does this help?
Is there any way to get these files using PowerShell or MSBuild or something like that? In other words, is there any command line equivalent to the Project > Store > Associate App with the Store... wizard?
No, as @William's explanation. The associating operation needs user's interaction in Visual Studio, this doesn't depend on a public command/API.
In my experience, we need to store(maintain) the latest store association information in somewhere, overwrite the related files and replace the reserved keywords in the app's manifest template file before packaging.