Multiline codeblocks via three backticks on each enclosing line:
I'm actually using that to manage my evergrowing AHK-scripts.
Whenever I make a change to a function or hotkey, I'll keep the old version and add some checkboxes for further possible improvements.
Doesn't have code highlighting or even line numbers of course, but I'd work on the scripts in Sublime or Scite4Autohotkey, anyway.
Obviously this isn't a hardcore programming workflow, it's just AHK scripting.
But considering that the language is devilishly difficult (for the strangest reasons), being able to link reference pages I don't quite understand, Discord conversations on their server and scripts I'm having trouble to make work has been helpful.
re: integrations, task management and such
An API or IFTT-integration is sorely missed.
You're right, out of the box it isn't great. But truthfully nothing else is either.
And trying to work with Windows and iOS..... well.... I mean..... how brave of you. I'm yearning for the day, I can ditch Android phone for something like a Surface Neo, so I don't have to deal with two OS.
There is no good software for combined task/project/knowledge management and spliting those things up, obviously means massive overhead.
However TheBrain has been the tool, that I've stuck with for the longest (close to a year now!) after having gone thru dozens in the past.
And I'm currently implementing Andy Matushak's Evergreen-notes approach with it: