How to enable package restore from a script on a solution from StudioShell console

EPR.ps1

Add-Type -AssemblyName NugetConsole.Host.PowerShell

#
# These functions are from Nuget test sources, the key here is to get access to an IVsPackageSourceProvider instance.
#

function Get-Interface
{
    Param(
        $Object,
        [type]$InterfaceType
    )
    
    [NuGetConsole.Host.PowerShell.Implementation.PSTypeWrapper]::GetInterface($Object, $InterfaceType)
}

function Get-VSService
{
    Param(
        [type]$ServiceType,
        [type]$InterfaceType
    )

    $service = [Microsoft.VisualStudio.Shell.Package]::GetGlobalService($ServiceType)
    if ($service -and $InterfaceType) {
        $service = Get-Interface $service $InterfaceType
    }

    $service
}

function Get-VSComponentModel
{
    Get-VSService ([Microsoft.VisualStudio.ComponentModelHost.SComponentModel]) ([Microsoft.VisualStudio.ComponentModelHost.IComponentModel])
}

function Enable-PackageRestore {
    if (!$dte.Solution -or !$dte.Solution.IsOpen) 
    {
        throw "No solution is available."
    }

    $componentService = Get-VSComponentModel
    
    # change active package source to "All"
    $packageSourceProvider = $componentService.GetService([NuGet.VisualStudio.IVsPackageSourceProvider])
    $packageSourceProvider.ActivePackageSource = [NuGet.VisualStudio.AggregatePackageSource]::Instance
    
    $packageRestoreManager = $componentService.GetService([NuGet.VisualStudio.IPackageRestoreManager])
    $packageRestoreManager.EnableCurrentSolutionForRestore($false)
}

Enable-PackageRestore