I am considering on buying the next Monthly Bundle if yes. I saw that it includes a "sneak peak," but will we eventually also get the Steam Key along with it?

Thanks in advance if anyone knows!

Nope! Humble Sneak Peek is just a demo!

You can however get the closed beta + a game key (if you pledge $20 or more lifetime once the game comes out) on my Patreon page.

Glad you like it!