I was part of the same separation wave. I was fortunate enough that a few people gave me a heads-up yesterday that final paychecks seemed to be hitting accounts already. I looked it up via GSS to confirm everything was accurate.
We no longer have access to GSS as you've discovered, smh. If you haven't received your final paycheck yet (mine and others I know hit yesterday), anything afterward is reportedly mailed to your home address. If you check their separation portal, there's also a phone # to the Employee Center they refer us to w/ any questions about that piece.