Noisli might be a bit more popular than Manuskript. We know about 1 link to it since March 2021 and only 1 link to Manuskript. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
Looks like you want something that integrates well with your workflow. The closest to your description seems to be Manuskript although I haven't used it. But your requirement of "keeping notes and frameworks and linking back and forth" should be possible by stitching together existing Linux tools using a syntax like markdown or asciidoc so that you can use any text editor to write your story and use external tools... Source: almost 3 years ago
I use a website called noisli.com for the background noise. You can give it a try if you would like to. Source: about 1 year ago
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
Noizio - Feeling that the noise of the big city is too much for you to bear?
yWriter - Free writing software designed by the author of the Hal Spacejock and Hal Junior series. yWriter6 helps you write a book by organising chapters, scenes, characters and locations in an easy-to-use interface.
MyNoise - Custom shaped online noise machines. Many Many generic sounds
StoryMill - Developers and publishers of Mac, Win, and iOS productivity, home and office and writing software such as MacGourmet, Paperless and many more. Based in MN.
A Soft Murmur - Ambient sounds to wash away distraction.