If I remember correctly, he wanted to fix the web search UI to match the features offered by Discord. He even crowdsourced some free work from his followers by asking them for help in implementing visual pills in text fields or something like that.

The basic feature set he wanted to implement wouldn't have been very difficult for someone who is experienced with react, but I'm imagining there's lots of minor quirks with the "last mile" of details related to internationalization / localization and accessibility.