This book should come with a warning - you cannot read it without a cup of tea in hand.
Sibling Dex lives on a moon of a planet that is not Earth. Their live is good: they are loved and comfortable and have what they need, but they are not satisfied with their life. So they become a tea monk - providing a listening ear and a cup of tea for those in need. They ride around in a home pulled by a bike touching the lives of many until they again are not satisfied with their existence. Then they diverge from their own path into the wilds where they come across a robot, Mosscap.
It has been years since the robots gained sentience and moved to create their own communities no longer mixing with people. Dex and Mosscap are quite different, but they slowly start talking and learning from each other.
This book is simple and a quick read. The characters are three dimensional and delightful and kind. The moon is coming back from the brink of disaster through sustainable practices. A Psalm for the Wild-Built quietly asks the big questions about existence. Read this book, maybe even read this book twice.