OK so the headset on the Giants is called a "zerostack". The Glory, Faith and Reign X all use a 1-1/8"-1.5" taper. You have a couple of options, none of which is super easy. Cane Creek sells individual pieces (upper and lower cups) so that you can design your own system. BTI stocks them and you can get them at any good bike shop.
If you are running an 1-1/8th steerer, this is the page for your bottom cup https://www.bti-usa.com/public/item/DC1017
If you are running a tapered steerer, this is the page for your bottom cup https://www.bti-usa.com/public/item/DC1015
This is the link for the upper cup https://www.bti-usa.com/public/item/DC1003
Your local shop should be able to help you further. I believe that e.13 makes a reducer you can press into the frame. Haven't installed/used one of these yet though. Hope that helps
If you are running an 1-1/8th steerer, this is the page for your bottom cup https://www.bti-usa.com/public/item/DC1017
If you are running a tapered steerer, this is the page for your bottom cup https://www.bti-usa.com/public/item/DC1015
This is the link for the upper cup https://www.bti-usa.com/public/item/DC1003
Your local shop should be able to help you further. I believe that e.13 makes a reducer you can press into the frame. Haven't installed/used one of these yet though. Hope that helps