How to add a MS365 group to many SharePoint sites as Site collection administrator

Naligurtan 

You will need to Modify this one to fit your needs such as looping through the CSV/excel but it should give you a base and understanding:

#Parameters
$SiteURL = "https://contoso.sharepoint.com"
$GroupOwner= "email address removed for privacy reasons"
 
Try {
    #Connect to PnP Online
    Connect-PnPOnline -Url $SiteURL -Interactive
 
    #Get the Site
    $Site = Get-PnPSite -Includes GroupId
      
    #Add Group to Microsoft 365 Group connected to the site
    Add-PnPMicrosoft365GroupOwner -Identity $Site.GroupId -Users $GroupOwner
}
Catch {
    write-host -f Red "`tError:" $_.Exception.Message