I would recommend that if you want to sell here, you upload the game here. Many people here do not go to Steam at all.
From the FAQ: https://itch.io/docs/creators/quality-guidelines#avoid-only-uploading-keys-or-li...
Avoid only uploading keys or links to other stores
Please try not to upload just Steam keys, or put a link to your Steam store page without uploading any files. Someone buying a game on itch.io wants to to be able to access it on itch.io through our website and app. If possible, your uploads should be DRM free, but it isn’t a requirement.
If you're concerned about maintaining multiple builds, please try out our command line tools. They're significantly easier to use than anything provided by any other store or platform. You can even find integrations with popular game engines.