If you’ve also written the game with Borogove, you can go to the Share tab and click the “Download Web Site” button to get a zip file that you can upload to Itch as is and it plays inside the “Run game” window. If you used the offline Inform 7 editor (I’m assuming this is an I7 game) you can add a “Release along with an interpreter” directive and then zip and upload the interpreter it creates, although IIRC the interpreter might be so old that it won’t show images.
Nils’s iframe trick is a Russian doll of a website inside another website inside another website, but if it works it works 