Yes, you can use Dabble to write non-fiction, but Dabble's current focus is fiction.
Any non-fiction that is similar to fiction would work great on Dabble, but if your non-fiction has a lot of additional needs, such as footnotes, special formatting for callouts or tips/tricks, a table of contents that you don't want to add after finishing, then Dabble may not be your best option. These are all things we'd like to add in the future though!