@Monk, David Thank you for posting question on Microsoft Q&A,
You may use the cmdlets from Az.ManagedServices module to get the details related to Azure Lighthouse onboarded customer. Especially, the following
Get-AzManagedServicesAssignment
Get-AzManagedServicesDefinition
Hope this helps.
If the answer did not help, please add more context/follow-up question for it. Else, if the answer helped, please click Accept answer so that it can help others in the community looking for help on similar topics.