Pure colour / Sheila Heti.

Enhanced descriptions from Syndetics:

Winner of the 2022 Governor General's Literary Award in Fiction
Shortlisted for the 2023 Rathbones Folio Prize in Fiction
Named a Best Book of the Year by The New York Times , The New Yorker , Vulture , The Times Literary Supplement , and more

Pure Colour is a galaxy of a novel: explosive, celestially bright, huge, and streaked with beauty. It is a contemporary bible, an atlas of feeling, and an absurdly funny guide to the great (and terrible) things about being alive. Sheila Heti is a philosopher of modern experience, and she has reimagined what a book can hold.

Here we are, just living in the first draft of Creation, which was made by some great artist, who is now getting ready to tear it apart.

In this first draft of the world, a woman named Mira leaves home to study. There, she meets Annie, whose tremendous power opens Mira's chest like a portal--to what, she doesn't know. When Mira is older, her beloved father dies, and his spirit passes into her. Together, they become a leaf on a tree. But photosynthesis gets boring, and being alive is a problem that cannot be solved, even by a leaf. Eventually, Mira must remember the human world she's left behind, including Annie, and choose whether or not to return.