Any DDR4 up to 2666mhz will work just fine. If you want to add more ram on top of what you already have, buy another one of the same module. Just search by the model number you see on the memory module and you're good to go.
I had good success with Gskill on a G752 VY all 4 sticks including the ones hidden where you have to take it apart. I found 2400 was the end of the clock no matter what you put in there. Conversely I did another machine finding the Hynix memory to match what was there and it worked fine also.
Looks like your stock is 2666 so you can run 2666 but Id either find exact sticks or replace them all.