SharePoint Online: How to Deploy a Design Package Solution (WSP) using PowerShell?

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"

Function Deploy-SPOSolution()
{
  param
    (
        [Parameter(Mandatory=$true)] [string] $SiteURL,
        [Parameter(Mandatory=$true)] [string] $WSPFilePath,
        [Parameter(Mandatory=$False)] [Int] $MajorVersion = 1,
        [Parameter(Mandatory=$False)] [Int] $MinorVersion = 0
    )

    Try {
        #Setup the context
        $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
        $Ctx.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.UserName,$Cred.Password)   

        #Get the Solution Gallery
        Write-Host -f Yellow "Uploading WSP File to Solution Gallery..."
        $SolutionGallery =  $Ctx.Web.Lists.GetByTitle("Solution Gallery")
        $SolutionGalleryRootFolder = $SolutionGallery.RootFolder
        $Ctx.Load($SolutionGallery)
        $Ctx.Load($SolutionGallery.RootFolder)
        $Ctx.ExecuteQuery()

        #Get WSP File Name from Path
        $WSPFileName = $WSPFilePath.Substring($WSPFilePath.LastIndexOf("\")+1)

        #Upload the WSP to the solution gallery        
        $WSPFileStream = New-Object System.IO.FileStream($WSPFilePath, [System.IO.FileMode]::Open)
        $FileCI = New-Object Microsoft.SharePoint.Client.FileCreationInformation
        $FileCI.Overwrite = $True
        $FileCI.ContentStream = $WSPFileStream
        $FileCI.URL = $WSPFileName
        $UploadedFile = $SolutionGallery.RootFolder.Files.Add($FileCI)
        $Ctx.Load($UploadedFile)
        $Ctx.ExecuteQuery()
        Write-Host -f Green "`tUploaded WSP File to Solution Gallery!"   

        #Install the solution
        Write-Host -f Yellow "Installing Solution..."
        $WSP = New-Object Microsoft.SharePoint.Client.Publishing.DesignPackageInfo
        $WSP.PackageGuid = [System.Guid]::Empty
        $WSP.PackageName = $WSPFileName
        $WSP.MajorVersion = $MajorVersion
        $WSP.MinorVersion = $MinorVersion

        #Install the solution from the file url - This creates a solution according to the Major and Minor Version
        $WSPFileURL = $SolutionGallery.RootFolder.ServerRelativeUrl + "/" + $WspFileName;
        [Microsoft.SharePoint.Client.Publishing.DesignPackage]::Install($Ctx, $Ctx.Site, $WSP, $WSPFileURL)
        $Ctx.ExecuteQuery()
        Write-Host -f Green "`tInstalled the Solution Successfully!"   

        #Activate the solution
        Write-Host -f Yellow "Activating the Solution..."
        [Microsoft.SharePoint.Client.Publishing.DesignPackage]::Apply($Ctx, $Ctx.Site, $WSP)
        $Ctx.ExecuteQuery()
        Write-Host -f Green "`tActivated the Solution Successfully!"

        #Remove the original wsp file uploaded
        $UploadedSolutionFile = $SolutionGallery.rootFolder.Files.GetByUrl($WSPFileURL)
        $UploadedSolutionFile.DeleteObject();
        $ctx.ExecuteQuery()

        Write-Host -f Green "`n*** WSP Deployment has been successfully completed!***"
        }
    catch {
        write-host "Error: $($_.Exception.Message)" -foregroundcolor Red
    }
}

#Set Parameters
$SiteURL = "https://crescent.sharepoint.com/sites/creditpipeline"
$WSPFilePath  = "C:\Users\salaudeen\Desktop\Crescent-Projects-v2.wsp"

#Get Credentials to connect
$Cred = Get-Credential

#call the function to deploy the solution
Deploy-SPOSolution -SiteURL $SiteURL -WSPFilePath $WspFilePath