Love the vibe, and the way it all fits together. It's a really nice proof of concept, and I reckon that all of it can be expanded nicely.
For me, the experience felt more like I was collecting poetry, and I think that should be leaned into. Maybe as you explore you collect vocabulary (inspiration), and then you let players put that together fridge-poetry-style. Alternatively you could do something like the poetry or songs in Kentucky Route Zero.
Also, I hit a few bugs with the book. I got the wrong flowers popping up in the book after interacting with the environment. It might have something to do with the sequence of interaction? And that's totally variable from the player's perspective where the goal isn't clear from the beginning.
Music is sweet, art is fire. Probably your best work yet! Totally love the book illustrations. For me, I want more book time.
I think it's not quite clean enough for a writing-prompt game (see Trawl), and not quite deep enough for an exploration/discovery game, but it could go either way, or both, and maybe some proc-gen would do it good in both areas.