External Content

"msix": { "allowExternalContent": true }

Default false. Set to true for sparse MSIX packages – packages whose payload lives outside the .msix file (registered via Add-AppxPackage -ExternalLocation).

Niche but useful for IT pros and large unpackaged-but-identity-needed Win32 apps – you get an MSIX identity (and the modern Windows features that come with it) without re-shipping the entire payload inside the package.