A simple feature I’d love to see implemented here is the ability for a member to increase the amount they want to pay above the minimum.
On Patreon, this looks like an input field at checkout, with a minimum tier price as the default. You can also see the idea in use on Itch.io and Bandcamp, where an item is priced at a specified minimum but can be (and usually is, in our experience) increased by the buyer on purchase. I’d bet that’s the case for most independent creators, given the option.
Not only would this make it easier to transition from Patreon without losing the additional income, it could also serve as a makeshift solution for the lack of monthly tiers.