When connected to a SharePoint site with PowerShell PnP, list all groups and the group members. The script will not show any kind of permissions.

GetGroupsAndMemberships.ps1

Write-Host
Write-Host "Groups Overview"
Write-Host "==============="
Write-Host

$groups = Get-PnPGroup

foreach ($group in $groups)
{
    Write-Host $group.Title
}

Write-Host " "
Write-Host "-----------------------------------------------------------"
Write-Host " "

Foreach ($group in $groups)
{
	$groupTitle = $group.Title
	
	Write-Host "Group: $groupTitle"
	Write-Host $("=" * ("Group: $groupTitle").Length)
	Write-Host " "

	$users = $group.Users

    foreach ($user in $users)
    {
        $userTitle = $user.Title
        $userEmail = $user.Email

        Write-Host "$userTitle  ==>  $userEmail"
    }	
	
	Write-Host " "
	Write-Host "-----------------------------------------------------------"
	Write-Host " "
}