Get-SharePointExternalSharingReport

<#
.SYNOPSIS
    Reports external sharing settings across all SharePoint sites.

.DESCRIPTION
    Compares each site's external sharing capability against the tenant
    default and flags any site that is more permissive than the baseline,
    since site level overrides are easy to set and easy to forget about.

.EXAMPLE
    .\Get-SharePointExternalSharingReport.ps1

.NOTES
    Requires PnP.PowerShell connected to the SharePoint admin site.

.AUTHOR
    Shehryar Hassan
#>

$tenant = Get-PnPTenant
$sites = Get-PnPTenantSite

$report = $sites | ForEach-Object {
    [pscustomobject]@{
        Url               = $_.Url
        SharingCapability = $_.SharingCapability
        MoreOpenThanDefault = $_.SharingCapability -ne $tenant.SharingCapability
    }
}

Write-Host "Tenant default sharing: $($tenant.SharingCapability)" -ForegroundColor Cyan
$report | Where-Object MoreOpenThanDefault | Format-Table -AutoSize