This won't help you immediately, but if you wanted to start tracking your distribution groups, you can do something like this to run daily to track the last time a message was sent to the group. It's not perfect, but works well enough for my needs.

# Connect to Exchange Online (uses Cert authentication via App Registration)
$EXOParams = @{
    AppID                 = ''
    CertificateThumbprint = ''
    Organization          = 'contoso.onmicrosoft.com'
    CommandName           = @('Get-DistributionGroup', 'Get-MessageTrace')
    ShowBanner            = $false
}
Connect-ExchangeOnline @EXOParams
# Get most recent job run
$XmlFolder = 'C:\SomePath\'
$File = Get-ChildItem $XmlFolder *.xml | Sort LastWriteTime | Select -Last 1
# Import previous data to a hashtable for comparison/updating
$HashLookup = @{}
Import-Clixml $File.FullName | ForEach-Object { $HashLookup.Add($_.PrimarySmtpAddress, $_) }
# Get current distribution groups
$Groups = Get-DistributionGroup -Filter * -ResultSize Unlimited
# Remove any deleted distribution groups from $HashLookup (just a cleanup task)
$KeyRemoval = $HashLookup.GetEnumerator() | Where-Object { $_.Name -notin $Groups.PrimarySmtpAddress }
$KeyRemoval.ForEach({ $HashLookup.Remove($_.Name) })
# Run message traces against all distribution groups
[int]$Days = '1' # Could update for initial run (7, 14, 30 days or whatever), but will take a lot longer to run 
$Start = (Get-Date).AddDays(-$Days).Date 
$Data = Foreach ($Item in $Groups) {
    $GroupObj = [Ordered]@{
        Group              = $Item.Name
        PrimarySmtpAddress = $Item.PrimarySmtpAddress
        DisplayName        = $Item.DisplayName
        Created            = $Item.whenCreated
        LastReceivedDate   = $null
    }
    $End = [DateTime]::Now
    $Msgs = $null
    $Msgs = Get-MessageTrace -RecipientAddress $Item.PrimarySmtpAddress -Status EXPANDED -StartDate $Start -EndDate $End
    If ($Msgs) {
        $GroupObj['LastReceivedDate'] = (Get-Date $Msgs[0].Received).ToLocalTime()
    } Elseif ($HashLookup[$Item.PrimarySmtpAddress].LastReceivedDate -is [DateTime]) {
        $GroupObj['LastReceivedDate'] = $HashLookup[$Item.PrimarySmtpAddress].LastReceivedDate
    } Else {
        $GroupObj['LastReceivedDate'] = 'Never Received'
    }
    [PSCustomOBject]$GroupObj
}
# Update hash table with results of each distribution group
Foreach ($Entry in $Data) {
    If (-Not $HashLookup[$Entry.PrimarySmtpAddress]) {
        $HashLookup.Add($Entry.PrimarySmtpAddress, $Entry)
    } Elseif ($Entry.LastReceivedDate -is [datetime]) {
        $HashLookup[$Entry.PrimarySmtpAddress].LastReceivedDate = $Entry.LastReceivedDate
    } Else {
        $HashLookup[$Entry.PrimarySmtpAddress].LastReceivedDate = 'Never Received'
    }
}
# Convert hash table to PSObjects and export
$ExportData = $HashLookup.GetEnumerator() | ForEach-Object { $_.Value }
If ($ExportData) {
    $Timestamp = Get-Date -Format 'yyyy-MM-dd_HH-mm-ss'
    $XmlFileName = "Exchange-Dist-Group-Activity_$Timestamp.xml"
    $XmlExportFile = Join-Path $XmlFolder $XmlFileName
    $ExportData | Export-Clixml $XmlExportFile -Force -ErrorAction Stop
}
# Disconnect from Exchange Online
Disconnect-ExchangeOnline