getallusersinaadgroups.ps1

if ($null -eq (Get-AzContext)) {
    Write-Host "No Azure Context... logging in."
    Login-AzAccount -UseDeviceAuthentication
}

$groups = @("bob","tim"
)

$outputPath = ""

Function Export-UserDetailsFromGroups {
    param(
        $affectedGroups,
        $outputPath,
        $processedGroups = @()
    )
    $i = 1
    foreach ($affectedGroup in $affectedGroups) {
        Write-Host "Getting group members and emails for $affectedGroup" 
        $i++
        if (($processedGroups.Contains($affectedGroup)) -eq $false) {
            $processedGroups += $affectedGroup
            $groupMembers = Get-AADGroupMembers -GroupName $affectedGroup
            foreach ($groupMember in $groupMembers) {
                if ($groupMember.Type -eq "User") {
                        Set-UserDetails -user $groupMember -outputPath $outputPath
                    }
                if ($GroupMember.Type -eq "Group") {
                    Export-UserDetailsFromGroups -affectedGroups $GroupMember.DisplayName -outputPath $outputPath -processedGroups $processedGroups
                }
            }
        }
    }
}

Function Get-AADGroupMembers {
    param (
        $GroupName
    )
    $groupMembers = Get-AzADGroupMember -GroupDisplayName $GroupName
    return $groupMembers
}

Function Set-UserDetails {
    param(
        $user,
        $outputPath
    )
    $csvStreamWriter.WriteLine(" $($User.Id), $($User.UserPrincipalName), $($User.DisplayName)") 
}

$csvStreamWriter = New-Object IO.StreamWriter "C:\Temp\userdetails.csv"
$csvStreamWriter.WriteLine("Id, UserPrincipalName, DisplayName") 
Measure-Command { Export-UserDetailsFromGroups -affectedGroups $groups -outputPath $csvStreamWriter }
$csvStreamWriter.Dispose()

Import-Csv C:\Temp\userdetails.csv | Sort-Object Id, DisplayName, UserPrincipalName -Unique | Export-Csv -Force -Path "C:\Temp\uniqueuserdetails.csv" -NoTypeInformation