Approve all updates with status "Needed" for a given computer group

[C0FFEEC0FFEE]

I'm trying to implement the following as a scheduled task:
1.) Approve all updates with status "Needed" for a given ComputerTargetGroup test_group (this is the group with the test systems that shall get all needed updates immediately)
2.) Approve all updates that have been approved for the test_group and are older than N days for a given prod_group (this is the group with the productive systems that shall get all updates after they have been approved for the test systems for N days)

I'm done with part 2 but am struggeling with part 1, because I can't get the list of updates with status "Needed" for a given computer group. It seems like Get-PSWSUSUpdate is missing a parameter or I am looking at the wrong commandlet?

Can you give me a pointer how to achieve this? If the feature is not yet implemented I could look into it.