I'm going to try a different combination for notes.
I had been writing in Markdown with IA Writer on iOS and macOS with iCloud as central storage.
Now, on iOS I am using GTW (https://gtw.app/); on macOS and Windows I'm using Visual Studio Code (it's a great editor in general); the central storage will be OneDrive. Then on Linux I can use the OneDrive web text editor. All still writing in Markdown.
Lets see how this works out.
Pretext also looks really nice on iOS, instead of authenticating through OneDrive directly, it accesses OneDrive via Files.app. And it has a more iOS-like UI than GTW.
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