Halo: Reach Character Pack

I am curious if anybody knows if you are required to buy Gears 5 Ultimate Edition or get the Xbox game pass to buy the Gears 5 Halo: Reach character pack or if you can buy Gears 5 alone and buy the Halo: Reach character pack separately. When I go to the pack right now it says I need a code to buy the pack, so is this because the game isn’t released yet, other than the early access? I don’t want to pre-order the game. I want to get it when it’s released. Anybody know, would be appreciated if anybody could explain.