If you read other threads, itch's stance is, that you should not rely on itch for promotion. They do not even guarantee you to get indexed. Though their faq is outdated regarding the waiting times.
Also, unlike certain other platforms, itch does allow you to link to your other platforms. So go ahead, upload it elsewhere and do your promotion on that other platform, if they have any options for that. But you can still have it on itch as well, wich might be good for your google results.