Wouldn't be fair. You don't get a itchio key when purchasing on Steam. Why not buy on Steam if you want to play there?
Honestly, this does come off as a bit of a rude response. I've played plenty of games on itch.io that provided steam keys when downloading. A nicer response would have been something along the lines of I am a new developer it is more difficult for me starting off. Especially considering the fact that i'm asking since your game will not open even though i paid on itch.io. :)
If you are experiencing technical problems, I don't think Steam would change anything =/. Contact us on the AGL DIscord and we can work with you directly. I want you to be able to play. Sorry if I sound rude, just trying to answer honestly and quickly. Cheers! -din