As SharePoint or Teams admin you can manage Microsoft 365 groups (create, update, delete, manage membership etc.) having your admin role activated. I use Azure registered app with “Group.ReadWrite.All” Microsoft Graph API delegated permission and Microsoft.Graph PowerShell module.

When a user was not a group member or group owner – and is added to the group members – user gets notification “You’ve joined the <Group Name> group” via e-mail that comes from a group e-mail address.

When a user is added to the group owners (or elevated to group owner if user was a group member) – user does not get notification.

When a user was a group owner and now is added to the group members – user does not get notification.

All the actions are logged into Microsoft 365 audit log under your personal Id.

Script samples:

# This script is just a sample to demonstrate basic technique on deletion m365 groups with PowerShell and MS Graph
# please do not run this script as is, but update it upon your needs

# authentication with personal Id
#  app must have as minimum "Group.ReadWrite.All" Microsoft Graph API delegated permission
#  user must have SharePoint admin (or Teams admin) roles activated
Connect-MgGraph -ClientId $clientid -TenantId $tenantId 
Get-MgContext | Select-Object Scopes -ExpandProperty Scopes

# sample data
$groups = @()
$groups += [PSCustomObject]@{GroupId = '443d22ae-683a-4fe4-8875-7bd78227a026' }
$groups += [PSCustomObject]@{GroupId = 'e5805388-c18c-48c0-b42d-6223cf8f3d82' }

# Get Groups
foreach ($group in $groups) {
    Get-MgGroup -GroupId $group.GroupId
}

# add members to the group
$groupId = '443d22ae-683a-4fe4-8875-7bd78227a026'
$userId = 'df74e0d3-d78c-495b-b47a-549437d93cf7' # Adele
New-MgGroupMember -GroupId $groupId -DirectoryObjectId $userId

# add Owner to the group
$groupId = '443d22ae-683a-4fe4-8875-7bd78227a026'
$userId = 'eacd52fb-5ae0-45ec-9d17-5ded9a0b9756' # Megan
New-MgGroupOwner -GroupId $groupId -DirectoryObjectId $userId

# Delete group
# add Owner to the group
$groupId = '443d22ae-683a-4fe4-8875-7bd78227a026'
Remove-MgGroup -GroupId $groupId

https://github.com/VladilenK/m365-PowerShell/tree/main/KBA/Ownerless-Groups