according to discord, the itch build had to be delayed by a few weeks.
But this demo here is something else anyway, if you were hoping to get the game for free due to the bundle.
Viewing post in Isles of Sea and Sky (Chapter 1) comments
I appreciate that that means it was different from a regular demo for you, and that you submitted it to a charity bundle you didn't profit off of.
I would still—personally!—prefer not to have demos in bundles in general, especially as the Itch megabundles add things permanently to your library if you download them.
On another topic, I'll add my voice here to the people who would be excited by a full Itch release. Valve gets more than enough of my money, and I rather prefer to pay to keep the lights on at the Itch headquarters instead.