If it does not work, then I guess the firm you are working for is pretty paranoid and the IT department are definitely pretty adept people that knows how to audit things and lock them down tightly.
I don't want to get too much in detail about the business. Over securing is one of our problem. We used to have a decentralized IT management, free for all paranoid local IT managers to do their own anal things. The shop is now trying to have balanced standard baseline that are less frustrating for the users while covering our ASSets.
Still, it is the first time I see a keyboard getting locked. I'll be talking with Deck directly and/or indirectly to investigate the issue. The keyboard is pretty much self sufficient for the configuration/programming. For the rest, as long as it sends the right keys to the OS, I don't give a crap if it lacks "extended" functionality as long as it works as a generic keyboard. To your point, maybe Deck could allow us to make it look like a Generic USB keyboard. That said, this is all speculation until I try Monday to disable the USB NKRO feature to see if it works.
This gives me another workaround idea though. The Deck Legend worked well with a USB-PS2 adaptor. Maybe I can get the Francium connected to the PS2 port.
I know security is paramount in places where there are secrets that are not meant to be shared but for them to even stop certain USB stuff from coming in is going a little over the top imo. Sure on the outside it seems to block USB flash drives for instance thereby preventing data leaks, but nobody said you can't swap out USB keyboard with a keylogger embedded inside that would trap all key strokes and pretend that it is a regular USB keyboard on the outside.
I guess they can push things even further (security-wise) by introducing thin terminals and instead regulate the "mainframe" instead. Though hopefully that won't happen. Novell delivered programs for instance.

) It is somewhat a good thing that there are business out there that are willing to listen to their employees when security is paramount. Leaving things overboard in terms of security is sort of what most IT security professionals would be willing to say, "security through obscurity". Not that I have any grudges against companies who treats security very highly as I have already worked for a few however, going through locking via USB for instance to certain keyboards is just weird.
The best way to test if the keyboard sends out the right keys is usually by testing it out on one computer. The last time I saw photos of Deck keyboards, it looks just like a mere standard keyboard on the outside with fancy printing on top and mechanical (Cherry MX) switches. In other words most of those keys should work as it is, anything that involves media keys may not work instantly if your firm provided you with normal keys without media keys for instance.
Yeah the only other way that I could see out of that option is definitely to make it seem like it is a firm or otherwise a regular keyboard. It is basically just rewriting the controller to spoof pretending it is just another "sheep" when it is actually a "wolf". This would most likely work if your firm only issues USB keyboards. If they blocked off USB then that is useless hence it would instantly refers to your latter point on using USB -> PS/2 adapters. Then again, there could be chances that your firm may also have blocked off access via PS/2 so you might want to keep that in mind.