I’d recommend Obsidian. Free and perfect for making and organising markdown notes, plus heaps of community extensions. And out-of-the-box you can make “canvas” pages where you can draw diagrams.

I’m interested to know more about what you mean by this.

Kagi

Reminds me of the surprised Pikachu meme

This looks to be closest

Your best bet is on their feedback forum here. There’s a good chance someones requested the feature you mentioned, in which case you’d be better off voting it than creating a new one.

Thanks for the laugh