"winget" is not available in Windows Sandbox by default. This script adds it.

Install-WinGetForWindowsSandbox.ps1

# Set up working folder
$wingetFolder = "$env:TEMP\winget-install"
New-Item -ItemType Directory -Path $wingetFolder -Force | Out-Null
Set-Location $wingetFolder

# Dependency URLs (v1.11.400 as of mid-2024)
$urls = @{
    VCLibs      = "https://aka.ms/Microsoft.VCLibs.x64.14.00.Desktop.appx"
    UIXaml      = "https://www.nuget.org/api/v2/package/Microsoft.UI.Xaml/2.8.6"
    AppInstaller = "https://github.com/microsoft/winget-cli/releases/download/v1.11.400/Microsoft.DesktopAppInstaller_8wekyb3d8bbwe.msixbundle"
}

# Helper to download a file
function Download-File {
    param (
        [string]$Url,
        [string]$Destination
    )
    Write-Host "Downloading $Url..."
    Invoke-WebRequest -Uri $Url -OutFile $Destination
}

# Download VCLibs
$vclibsPath = "$wingetFolder\Microsoft.VCLibs.x64.14.00.appx"
Download-File -Url $urls.VCLibs -Destination $vclibsPath

# Download and extract Microsoft.UI.Xaml from NuGet
$nugetPkg = "$wingetFolder\Microsoft.UI.Xaml.2.8.6.nupkg"
$extractedXamlPath = "$wingetFolder\Xaml"
Download-File -Url $urls.UIXaml -Destination $nugetPkg

Add-Type -AssemblyName System.IO.Compression.FileSystem
[System.IO.Compression.ZipFile]::ExtractToDirectory($nugetPkg, $extractedXamlPath)

# Find the correct .appx inside the extracted NuGet package (x64)
$xamlAppx = Get-ChildItem "$extractedXamlPath" -Recurse -Filter *.appx | Where-Object { $_.Name -like "*x64*.appx" } | Select-Object -First 1
if (-not $xamlAppx) {
    throw "Microsoft.UI.Xaml .appx not found."
}

# Download App Installer bundle
$appInstallerPath = "$wingetFolder\AppInstaller.msixbundle"
Download-File -Url $urls.AppInstaller -Destination $appInstallerPath

# Install all in correct order
Write-Host "`nInstalling Microsoft.VCLibs..."
Add-AppxPackage -Path $vclibsPath

Write-Host "Installing Microsoft.UI.Xaml..."
Add-AppxPackage -Path $xamlAppx.FullName

Write-Host "Installing Microsoft.DesktopAppInstaller (winget)..."
Add-AppxPackage -Path $appInstallerPath

# Install WinGet now that we have the desktop app installer
Install-PackageProvider NuGet -Force  
Set-PSRepository PSGallery -InstallationPolicy Trusted  
Install-Module Microsoft.Winget.Client -Confirm:$False -Force -AllowClobber  
Import-Module -Name Microsoft.Winget.Client  
Repair-WingetPackageManager -Force -Latest -Verbose