Flatpak appears currently the best supported. Many apps and tools can be loaded through it. The Snap system is not at this writing satisfactorily supported under Arch Linux, but it alone appears to contain PowerShell.
To use Flatpak under Arch, first you’ll need to install the Flatpak system:
pacman -S flatpak
and then you’ll want to download a .flatpakref file from flathub.org. Once you have that, run this:
flatpak install *.flatpakref
and the install will commence, it will install runtime prerequisites as needed.