We have uploaded a WM enabled game to itch.io to verify that the new "monetization" flag on the itch.io <iframe> tag works as expected. You can try the game here:

https://defold.itch.io/climberz (source code: https://github.com/defold/game-climberz)

For more inspiration we recommend that you check out theWinners in the Web Monetization category of the js13kgames competition: https://js13kgames.com/#winners-webmonetization