Since you mention it, one missing feature on itch.io is the ability to sell the web version of the game, like Outpan does. For example, all of my games have the exact same gameplay whether it's desktop or web, so it doesn't really make much sense to charge for the downloads while the full game is already free on the web. That's precisely why I'm only offering the desktop versions on itch.io while relying on Outpan for the web versions.
Viewing post in Monetisation Alternatives
That's interesting, I didn't know about Outpan. I see they have in-app purchases, too. I try to have all my stuff on itch.io, but for my bowling game I have the web version only on gamejolt, partly because I also want to support gamejolt, and partly because on itch.io I feel the webplayer dominates the game page and it's harder to see that there are also downloads. I think GameJolt has or had an ad revenue share option, but I'm not sure the status of that, I don't check it very often and I haven't had a payout from there in ages.