So, I did both artifact missions and finished them. It only shows me enhancements. I decided to finish the 330 hoping it will show them, but nope. I tried to talk to Hyde again but all he says is to "come back later".
https://imgur.com/a/fN4cFSg
Here is a screenshot of what I see.
https://imgur.com/a/33nOpMX
I am theorizing that because I chose artifact missions first instead of blue (prototype) missions, that might have broken the vendor. It's frustrating because I have to test this out on another character hoping that the same thing won't happen because of this bug. More waste of my currency...
***Update!***
I found a solution to this. You will need to have at most 328 item level on your character before talking to Hyde. He will give you the option to take the prototype missions. The prototype missions are the way to get the rest of the mods (armoring, barrel, mods). Hope this helps.