Yes, unfortunately itch isn't really built for that.
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I can very much sympathise with that feeling - subscribestar might be a better alternative for you.
As for itch, I'll certainly look more into it and see what other devs are doing, because I may well be missing something, but I suspect it won't work with my game being free, I think I'd have to make the game paid-for and then put out the public version as a free demo.