I'll speak to my own experiences here though as the spouse.
The NNSA is, like, bonkers important. I'll just copy-paste wikipedia here:
"The National Nuclear Security Administration (NNSA) is ... responsible for safeguarding national security through the military application of nuclear science. NNSA maintains and enhances the safety, security, and effectiveness of the U.S. nuclear weapons stockpile; works to reduce the global danger from weapons of mass destruction; provides the United States Navy with safe and effective nuclear propulsion; and responds to nuclear and radiological emergencies in the United States and abroad."
https://en.wikipedia.org/wiki/National_Nuclear_Security_Admi...
The reason it took until 2000 to make them is tied up with the silver tsunami and congress. But suffice to say, we really really need them. A lot of their stuff is very classified, but the presentation that I was allowed to attend were quite eye opening. Most of the presentations are on things like blast resistance in microsceonds of a door or some z-pinch magnetic experiment. But there were are lot on the national security picture at the time too. The main concern is that the nukes are aging. Stuffing 1950's breadboards next to that much radiation for 50 years wasn't the plan, we were thinking of using them a bit more quickly than that. But now we have them and can't be sure if they'll work. There are a lot of other issues too, big ones, but I'll let the interested people here discover more on their own.
Here's a list of conferences that can get you going on where to find more: https://nssc.berkeley.edu/events-and-programs/nssc-conferenc...
Youtube also has a lot of them online too: https://www.youtube.com/results?search_query=nnsa+conference
The general side I saw was in my spouse trying to be recruited by the NNSA to work for them after graduation. The silver tsunami is a big deal in DoD government. And the issue for us at the time was the very much lowered pay. One of the main sites was the square mile that is Livermore National Labs. But with a PhD in the right fields and the NNSA fellowship, my spouse could easily just go across the Dumbarton bridge for about 4x the pay and mostly just as good benefits (the retirement plans aren't quite as stellar, but only a little). So, this is where HN/tech and the NNSA merge: employee competition.
Now, I'm not surprised that they're reporting that a lot of the fired employees are not coming back. The big thing that they had going for them, personally, was 'the mission' and the quiet respect and admiration that the government and therefore the people of the US had for them and their sacrifices (classified work has a lot of sacrifice that is not seen, especially in nuclear work, much more so than beyond just pay).
That they were fired, likely by some random 20 something from DOGE (read: not a flag rank military officer (Admiral+) or an elected official of national office (Senator+)), without notice, last Thursday. Man, that hurt the ego a lot, and fundamentally altered the bargain that they had with the government and the US people in general (from what very little I knew of those people).
It is going to be very hard to get them all back to begin with, let alone for that same payscale and benefits schedule. That gap for 'fired with cause' is going to mess up the retirement in a way that is currently hard to fix (AFAIK). Many of the NNSA are just going to go get a better job, really.
And the US is going to be left behind in the nuclear arms race that is still very much going on.
Summary: Pardon my french, but, this is a big fuck up.