How to find Unassociated/Orphan Azure Alert Groups

I have many subscriptions where users earlier created different Azure Alert Action Groups. Now I'm in the process of cleaning those unassociated or orphan Action Groups (Which are not associated with any Alert Rules)

Is there a way to query (API/CLI/PowerShell/Graph Query) to fetch the list of unassociated Action Groups?

I have followed and taken code from @Juval's answer , I have tried to reproduce in my environment and got expected results as below:

az login
$x=az graph query -q "Resources| where type == 'microsoft.insights/actiongroups'| project name"
$m=$x | ConvertFrom-json
$v=$m.data.name

$y=az graph query -q "Resources| project alertName = name, location, type,props = properties| where type contains 'microsoft.insights/activitylogalerts' | mvexpand actionGroups = parse_json(props['actions']['actionGroups'])| extend actionGroup = extract(@'([^\/]+$)',1,tostring(actionGroups.actionGroupId))| union (resources| project alertName = name,location,type,props = properties| where type contains 'microsoft.insights/metricalerts'| mvexpand actionGroups = parse_json(props['actions'])| extend actionGroup = extract(@'([^\/]+$)',1,tostring(actionGroups.actionGroupId)))|project actionGroup" | ConvertFrom-Json

$t=$y.data.actionGroup 


$diff = Compare-Object $v $t
$result = $diff | Where-Object { $_.SideIndicator -eq "<=" } | Select-Object -ExpandProperty InputObject
$result

Output:

Here $v contains all the action groups names.

$t contains the actiongroup names associated with alerts.

$result contains the names of action groups which are not associated with alerts.