Thanks all for the replies. I did reach out to the contact Crankycrank provided and got a quick and helpful response. Here it is:9 speed:
X9 NPGY (silver outer plates and grey inner plates) is our new name for X9.93
X9 NPNP (full silver) is our new name for X9.99

Comment: We found the 93 and 99 names to be confusing so we simply reverted back to the outlooks for descriptions. Both of these chains have the same durability with the only difference being coating. The NPNP will have better protection from rust specifically on the inner plates.

MSRP should be around USD20. Anything much cheaper than that is likely fake.

11 speed:
Same comments for X11 NPGY = X11.93.

We dropped the 93 and 99 model names a few years ago, including renaming many of our multispeed chains for simplicity overall (Z6 = 6 speed, Z7 = 7 speed, etc), but it’s taking a while to completely filter through the market. Sorry for the confusion. Let me know if you have any other questions.