I tried to grab the card by going to sandbox mode and then deleting the door and then mailing myself the key, but the mailbox function isn't working or something.
That option is out. I have seen that you might be able to do the chair glitch where you sit on a chair in someway and then when you exit it puts you on the other side, but I don't quite know how to do that one.
I tried grabbing an object, slotting it through the hole, going to the side of the building so that I am holding the object through the wall and knocking the keycard down the steps (which should teleport the key to the top to prevent softlocks). That didn't work so I tried to use explosions to dislodge it.
I found out that none of this worked because the keycard acts like the burgers where you have to (press E) on it before you can actually interact with it. It can't be knocked out of the way or interacted with unless there is some mechanic that I don't know about. I assume this is done so that random explosions can't softlock you out of the keycard or the keycard teleports on top of the bunker and then gets launched by another explosion. Making it impossible to find in those bushes.
If you have any other ideas let me know, but I am stumped.