Random assortments of stuff post okay?

Better create giveaways. All discussions are open for unregistered users and too many bots will insta claim your keys.

I think you can... but you will just let the bots get them all in the first 10 seconds :)

There is an open thread https://www.steamgifts.com/discussion/hK2kQ/orphan-keys-drop-thread for keys like that.

Do note that the Orphan Keys Drop Thread is the absolute worst choice for those who care about where their keys go, as those offering keys are almost guaranteed to not get a reply even if they puzzle-lock the keys, nevermind all the bots hugging the thread for unprotected keys. The whole thread is just a key-mining operation by this point, considerate site users be damned.

As recommended by Arwiee, groups are your best bet for that kind of thing, if you have Steam keys you're uncertain about. You can also just solicit people through a thread [eg, "Comment if you want any of these games, I'll pick people randomly to add on Steam to give the keys!"]. There's a lot of ways to do it and you're basically okay to do most any approach you want, so long you're not locking the keys behind advertising-related tasks or offering non-Steam keys through the core giveaway system.