It wasn’t on Steam until 0.5, so this isn’t an option.
All you need to do to upload it is get the zip file and putting it in the upload area so then other people can download it and you may add an additional price to it if you want... at least that is what i read on this website: https://itch.io/t/959114/how-do-i-upload-a-downloadable-game#:~:text=You should probably check online,to make your game portable.&text=For Unity, zip the entire,That's it! copy and paste it to the address bar and then go to it to view the entre thing on your own time if you want