I agree that some kind of subscription donation or outright subscription service would improve the options. I would also like to see a button to add a tipp to Itch, instead of relying on the developer to give a share. Also, it should be fixed that people can increase their payment to access higher reward tiers. Or donate again without buying the game again.
But I would also like to point out that patreon in principle is a pay per content service and not an extended kickstarter to finance a long term project. You cannot finance it with a fixed sum and will get the finished game. It is more suited to literally patronize in the sense of support the works of a content creator.
While Itch is a pay per project service. With lot's of "early access" projects. Subscription for an early access game. Does sound a bit wrong, does it not.