I read the books first, but I thought the show did a great job of capturing the feel and the story beats with only minor character rearrangement. I believe I read that the authors (they're a duo who originally wanted to make a space board game, I think?) rewrote and combined some characters from the show, so nothing seemed really out of place in either retelling

Not only are there 9 books, but there are also novellas in between that give extra context if you're interested, but they're definitely not required.