Hasn't the federal process for restoring gun rights been "defunded" for many many years and thus currently impossible?
Yes, but the NICS Improvement Act did set forth procedures to get removed from the system in regards to mental disqualifications at the federal level. Basically, you can petition the body that said you were disqualified to say that you are no longer insane. They have to remove you if you are able to manage your own affairs or have completed treatment. If they deny you or fail to act, you can file a claim in federal court.
This only applies at the federal level. States are supposed to set up their own programs. Most have not.