Can I filter users who have no signInActivity?

[DaveLhx]

So I have read and used the method here https://docs.microsoft.com/en-us/azure/active-directory/reports-monitoring/howto-manage-inactive-use... to check for users who have been inactive for X time.

A filter like this is suggested 
https://graph.microsoft.com/beta/users?filter=signInActivity/lastSignInDateTime le 2019-06-01T00:00:00Z

But this does not work for people who never logged in and have no signInActivity and cant seem to find a way to filter on it being null or empty or whatever.

Do I have to fetch all the users and filter locally on that dataset?

[#2]

Filtering in Graph remains quite limited, so it's very likely that you have to do thing client-side. If you do come up with a filter that actually does this, please share :)