well you can buy the full version when it comes out.
Additionally I have a patreon and backers get spoiler updates, the ability to beta test new versions, and all patrons get a free version of the final game.
I was also thinking of releasing a demo 2.0 (that covers the first third of the game) + a digital art book that would be a 'pay what you want' to specifically cover the costs of commissioning the musician.
Other than that I am just glad you enjoyed the demo. I hope you will enjoy the full version once I finish it.