Only supported in the Beta Graph endpoint as of today, but I recon it would look like this:

Extend the List o365group command to list all the deleted Office 365 groups

• command: graph o365group list --deleted
• requires connection to the Microsoft Graph (Add support for authenticating to MS Graph #10)

I don't think we need filter options (PowerShell does not support them as far as I know) but we might want to provide paging as you can have a whole bunch of deleted objects. Is there paging support in listing groups?