Slightly less "Quantum is an advertising term only used when you have nothing innovative" than usual! They're apparently using a QRNG (Quantum random number generator), instead of the usual CSRNG (Cryptographically Secure pseudoRandom Number Generator). This is hypothetically more secure, but in practice there's no difference and this is purely a marketing gimmick.
If a custom rom can’t support it, that’s more about the custom rom than Samsung here. They will almost certainly open source the kernel driver part, and any user library could be copied from the stock rom if absolutely necessary. If a rom developer doesn’t want to do that, well that can’t be reasonably pinned on Samsung.
I disagree, if this chip is anything like Knox protection, it will self-destruct if tripped, which is intentional to prevent the rom dev from making use of it.