When I say "out there" I mean books that cover topics and perspectives that are rarely hyped up in popular conversations around what people read. Like everyone can find a popular video recommending self-help productivity nonfiction or YA #relatable fiction but a recent fiction book that blew me away was "I'm thinking of ending things", it got a movie adaptation on Netflix but after the movie came out very little conversations about the book carried on. Fair warning, the book "I'm thinking of ending things" is a horrifically bleak exploration into the mental state of someone contemplating suicide at the end of his life and his reflections about himself and his mistakes throughout the years are not helpful if you're looking for a good time. But I've never seen a story go that far in depicting someone's mental state in that kind of situation so it blew me away but is also underrated imho.
You might try gateway. First book of heechee by Frederick pohl. The science is a bit wacky (think 1960s people thinking we would be on the moon with lasers in space 1999) but there are themes of depression and mental health. I'm not sure if I could suggest the rest of the books, but gateway is pretty solid imo.
I'm in the middle of trying to make aspects of it into a mod for stellaris right now but I'm not a good writer so I'm procrastinating!
Wacky science is fine with me, it's the overly long dry expositions that tend to turn me off of the more old school sci-fi stories like Dune. Will definitely give Gateway a try so thank you for the recommendation!