Per my conversation with admissions, all GA positions have been filled. Merit based financial aid includes Assistantship opportunities. You would have to ask about Research positions, although you would be competing with current Wagner students for those.
Since Wagner is government and nonprofit focused, they seem to not offer significant funding for many incoming students because they know you can enroll in the Public Service Loan Forgiveness Program (PSLF). As most of you are aware, you take out Direct Federal loans, pay back through Income Based Repayment (IBR), PAYE or REPAYE program