Summary of the new feature/enhancement

For Snap and AppX packages of PSCore6, $PSHOME is effectively read-only. Any configuration stored in $PSHOME needs to be in a different location. On Windows 10, it would make sense to be in $env:SystemDrive\ProgramData.

Register-PSSessionConfiguration stores the config file in $PSHOME\SessionConfig folder.

powershell.config.json for the system is stored in $PSHOME, this means that admins can't set system wide config and cmdlets like Enable-ExperimentalFeature -Scope AllUsers won't work.

Update-Help -Scope AllUsers also won't work as it's stored in $PSHOME.

When this is fixed, test changes relying on Test-CanWriteToPsHome should be reverted.

Update — scope narrowed; solved via the MachineFolder data store

The pieces this issue originally enumerated are now split up:

• System-wide powershell.config.json and Enable/Disable-ExperimentalFeature -Scope AllUsers → handled by the config relocation: design [Design] MachineFolder: a per-machine writable data store for MSIX-packaged PowerShell #27697, implementation PR Place System-Wide Config in the Machine Folder for MSIX Packages #27632.
• Update-Help -Scope AllUsers → now tracked in PS7-packaged: Update-Help -Scope AllUsers fails under MSIX ($PSHOME read-only) #27699.
• Test-CanWriteToPsHome test reverts → revisited as each piece lands.

This issue is narrowed to the SessionConfig .pssc write-location: Register/Set-PSSessionConfiguration copy the .pssc into $PSHome\SessionConfig (Utils.DefaultPowerShellAppBase, CustomShellCommands.cs:950), which is read-only under MSIX. The fix mirrors the profile relocation — Utils.GetPackagedMachineDataStorePath() ?? AppBase + \SessionConfig.

WinRM / remoting activation under MSIX (native pwrshplugin.dll registration) remains a separate concern tracked in #27563. Tracked under #27565.