itch.io

maybe instead of having it able to give discounts ONLY to patreon instead some system that allows a 1 time useage coupon code to be sent to someones email then regardless of what platform you use you can just supply a mailing list (idk say in csv) and it will send a 1 time code to everyone on that mailing list then if you have patreon you just download your mailing list and use that to send out coupons if you have go fund me or some crowdsourcing page you can use that to send out coupons to people