Checking into itch's systems, it seems a little rigid. Every way I look at it has some flaw to it making it non-ideal.
Like it seems as though it doesn't have an actual subscription system, but I could set a flat price for a build for example to be sold. Then I could 'increase the price' to maintain your access to the new builds for example. That would work except I would like it that if you support me during the dev cycle that it's cheaper for you than it would be when the game is released.
Anyway, I set up a Boosty. For now it will just host the builds, but if there is interest I will also host the npc polls there too when a month starts.