You can probably go to your local authorized Hyundai dealer to ask for the part number of the clip, or see if they have a few they could give to you for free / maybe like a pack for 10 bucks.

Found a bag of clips from amazon , link here. This could work as a replacement if you want to potentially save a trip to the dealer. I don't know for sure though, I just google searched "genesis coupe hood liner pin" and those showed up.

Alternatively you could just put on some adhesive film. Sound deaners (saw HR_Smutnstuff suggest dynamat), but you could also do like the gold reflective tape/film as a firewall.

Or, you can do what us BK1 folk do and run no liner... cuz we ain't get that fancy stuff :(