I'm pretty sure that a standalone build works even better than an installer, especially if the player is using the itch.io desktop app. I will say, though, that a large fraction of people who play jam games sort for only games that can be played in the browser, so I'd look in to building for WebGL in Unity. Just make sure that "Compression Format" is set to "Gzip" in Player Settings > Publishing Settings. Itch.io kind of breaks otherwise.