For many years PowerShell was a Windows-only thing that was part of the closed Windows ecosystem. Now a days PowerShell is open source up at https://github.com/PowerShell with lots of docs and scripts, also open source.
PowerShell is supported on Windows, Mac, and a half-dozen Linux distros.
While running PowerShell on your RaspberryPi is still experimental and only supported for Raspbian Stretch it’s running pretty smoothly.
Installing Install the prerequisites