There is a way to install unsigned .Appx App Package with PowerShell in Windows 11/10. Use the Add-AppxPackage command line to get it done easily.

Here is how to configure Windows 10 to install new apps in an external drive and various other information you need to know about this feature.

Fix This app package is not supported for installation by App Installer because it uses certain restricted capabilities, by following the suggestions laid down in this post.