@oosmoxiecode has released this lovely C64 styled post-processing WebGL shader. Seen running on-top of a trailer for the forthcoming Cyberpunk 2077 game. You can open the control panel and tweak the effects to alter the dithering. View source to see how the magic happens. As to be expected it’s powered with three.js and needs a WebGL capable browser, which thankfully are to be found pretty much everywhere these days.
Play with the C64 Shader Effect (warning: contains music, but great music