The author wrote a very simple MPEG[1] decoder, so there's an obvious benchmark for making that even simpler.
I personally wouldn't mind a Quite OK Page Description Langage. Something that gets you most of PDF/PS/HPGL without all the effort. Could use the Quite OK Image Format for bitmap images. Not sure whether you'd need a Quite OK Vector Format and/or a Quite OK Font Format as prerequisites…
Quite OK browser. It doesn't have webgl, webgpu or other fancy and easy to exploit stuff, but it renders 95% of websites and source code is easy enough to be maintained with very few people.
Quite OK JS Plotting Library (QOJSPL, nice, sounds like my cat walking on the keyboard). With an intuitive, documented API that doesn't require you to dig through tons of examples on sites that take ages to load. Because, no, a massive stash of non-orthogonal examples does not replace a documentation.
AKA last Tuesday morning frustration : I wanted to make interactive plots on a web page to explain math stuffs.