Have you heard of Manuskript[0]? It's an open source editor with a lot of features similar to Scrivener, runs on Linux/Windows/Mac, and has a few features that Scrivener doesn't have that have helped me plan things more fully in the past. It's not perfect, but it's a solid tool. Also, it's backed by Markdown text files.
[0]: https://www.theologeek.ch/manuskript/