Another good one is 'Abyss Explorations'. It's a collection of short stories that expand on different aspects of the 'Made in Abyss' world. Some stories are about the history of the Abyss, while others are about the daily lives of the characters. It's a great read for fans who want to explore more of the lore.
The answer is yes. Made in Abyss began as a novel. This original form allowed the creator to lay out the core ideas and storylines that were later brought to life in other visual and narrative formats.
The Made in Abyss manga is on hiatus for now. Maybe the author needs time to flesh out the story or there could be other behind-the-scenes factors affecting the schedule.