I really really wanna write because I've started to realize that writing helps with my mental problems, and earlier I found a prompt that I really like but I'm not sure it deserves a while book

Does this deserve an entire book or should I make it a chapter (or series of chapters) in a new book for prompts/requests/random ideas etc.
Sooooooooo since you guys are gonna be (hopefully :'I) reading what I write, what do you want?

Whole book?

Prompt book?