I think mdsilo meets your need. https://mdsilo.com/, it is a lightweight cross-platform desktop app, support attach local image or PDF files with relative path
mdSilo now comes to our desktops, It is available for Web, Windows, macOS and Linux now!
I build the mdSilo Desktop App with React and Tauri(Rust), the bundle is really tiny, it is not 90M or 100M+, it is only 3 - 5M, but the same powerful and versatile:
1, WYSIWYG markdown editor, slash command, hotkeys and hovering toolbar make the writing and formatting fun.
2, Different Linking and views help you store the ideas, thoughts, knowledge in the networked way and view them from different perspectives.
3, Daily note helps to track daily thought.
4, Inserting local Images into your writing makes the note colorful.
I guess there should be a wordle for each subject, like Nerdle for Math, worldle for Geography. And here is a wordle for History: https://peotik.com/otd/