I just wish there was a native Markdown renderer / editor library in C that I can use cross-platform - in the style of something like IMGUI (where the library outputs a list of primitives for you to render yourself in any graphics API).
Or well... since we now have Claude I might have a jab at this someday in my free time.
For just rendering (no editing) you could use https://github.com/litehtml/litehtml (C) or https://github.com/DioxusLabs/blitz (Rust).
Both are actually lightweight HTML rendering libraries, so you need to compile markdown to HTML to use them. But there are many libraries for that.