Redeem Steam key to account with Steam OpenID like Humble Bundle

Humble Bundle has started requiring the user to sign in through Steam's OpenID authentication where it then redeems the Steam key on the user's account. I was unable to find any documentation on this

Insanely clever Steam credential stealing scam using fake Sign in

13 simple ways to redeem Steam Games automatically (I made a

Steam New Profile Privacy Settings [ALSO, STEAMGIFTS 0 WISHLIST

Does Humble Bundle give Steam keys & how to redeem them

I randomly got this message today for a game I got in a Humble

Steam: How to activate a Game / redeem a Steam key? - Epic Bundle

How to Buy a Humble Bundle and Redeem It on Steam

Are steam game keys region-locked via Humble Bundle? : r/humblebundles

Do you have to redeem humble bundle keys on the steam account that

How to Buy a Humble Bundle and Redeem It on Steam

Anyway to find Steam keys that are revealed but not redeemed? : r