Will you ever add the option to buy the Full Patreon Version with a one-time payment on itch?
If what you need is to have access to the v1.0, you simply can pay $5 once on Patreon or SubscribeStar and call it a day. And then if a new version has something you want in it (let's say v2.5 adds mermaids and you love them), you can simply pay $5 a second time to get access to that version and everything that goes with it. Version 1.0 will be all you need to create scenarios, new versions after that will not change/alter previous in-game options, only add new ones. So scenarios/characters made in v1.0 will fully load and work in the free Scenario Player v4.7 for example. Also, v1.0 will have full mod support, so you will be able to add options by yourself.
If I were to make the project a one-time payment for an auto-updated version, I think that I would make it on Steam, and I would have to think about the correct price for it + give keys to previously supporting people. Again, I didn't think about all those things for now, since I'm still heavily working on everything as a one-man-band haha.
But if you only want a never updated v1.0, a purchasable v1.0 that stays a v1.0, then yes, I 100% could make a $5 option on here to buy that (but I don't want to mislead people, and that the risk of such option).
I hope that I answered your question! ♥