I need to do some post step stuff when Sitecore has been installed/set up (And no post step when solution has been built). And it seems that the poststeps folder in App_Data seems to be the way to go.
How does it work? For instance, when setting up SXA I've noticed this file in the poststeps folder: Sitecore.XA.Foundation.Installer.ExperienceAcceleratorWDPInstallationPostStep, Sitecore.XA.Foundation.Installer I assume it calls for method in assembly Sitecore.XA.Foundation.Installer(similar to a process in pipelines). Is it possible to call a Powershell script instead? Please advice :-)