Gotta say, it got entertaining by the end. But I think by then it also lost all sense of believability. That's not great. First third really read like something written to be made into a movie. The rest not so much. I don't know. My thoughts are all over the place.
EDIT: "Ryan Gosling to Star in Astronaut Movie ‘Project Hail Mary’" - lol, NO WAY! Isn't this a surprise!!!!!!!!! Mind "blown"