The only two possible courses have been mentioned several times, follow through the appeals process, and get a lawyer.
The OP said they already contacted a "2A" lawyer, who said he could not help.
Find another lawyer. (also make it clear with the first lawyer, did he mean "cannot help at all"? OR "cannot help at this time"? Could their response have been either of these, and all you got from it was "cannot help"?
(and if that turns out to be the case, look for another lawyer, anyway. Council who does not /can not be clear with you, will not be clear in court....)
Right now, I think no lawyer can help, other than to prepare for possible future action, and have a case ready to go, if it becomes needed.
Until the appeals process is done, you aren't "fully denied". (I consider this a legal fiction, but that's the system we have to work in.) Until the appeal process is complete, there is nothing for a lawyer to base a case on.
There MAY be a case against the Gov. for suspending appeals, but the viability of that will depend on how long the suspension lasts. A short period of reshuffling resources to deal with unanticipated work load is reasonable.
Failure to restructure resources to effectively meet ALL the obligations (after the crisis is past) is not acceptable.
This case is illustrative of a huge flaw in the system, one that is and has been the biggest fear of many of us. That we, while totally innocent of any crime, can be denied our right, due to a computer "glitch".
In this case, a person with a clean record, who has PREVIOUSLY passed is now denied. (not delayed, denied). Here the system is failing on three main counts, two are practical matters, one a fundamental principle.
#1) Wrongful denial. No, it shouldn't happen, but it can, and it does, the system isn't perfect, so there is an appeals process.
#2) Suspension of the appeals process. Bad! Wrong! FAIL!!!! Explaining it away as "temporary due to an unexpected volume" is an explanation, not an excuse for the failure.
#3) Failure of what I call the "moral justification" of the background check concept, as applied. (not unique to this case, it is an overall failure due to the way the system is applied. It is not the "nature of the beast", it is the nature of the beast they stuck us with!)
"to keep people who should not have guns from being able to buy guns" this is what we were told (and sold) was the purpose and the benefit of background checks. A valid ideal, one I cannot argue against in basic principle, it is the execution of that which I disagree with.
My particular point here is about having to pass a background check EVERY time you buy a gun. In some cases, you even have to pass the check to get your own property (a gun) back from a shop after having it worked on.
The reasoning that says "we need this system so that unchecked/unapproved (aka presumed dangerous) people will not be able to buy a gun to do violence with" becomes VOID when those people already HAVE a gun.
(and yes, I'm totally avoiding the argument about people willing to break the laws with violence being stopped, or not, by gun control laws)
Pro system proponents will argue that the check is needed everytime, because something might have changed, since the last time you bought a gun, and now, you might be a prohibited person, and so, cannot buy a gun.
That is regulatory compliance. It does not make the public any safer. (because the person in question already HAS a gun (or 3, or 50) and if they are going to do violence with it, no law will stop them.) SO, checking people who have already guns is a waste of time, money and resources, IF you believe in the stated purpose of the entire background check concept.
And, its most likely result is seen in the situation of the OP, a false denial.
