Nice idea, and the core insight is right: for young kids the danger isn't YouTube itself, it's the recommendation engine; one video ends and three more autoplay before a parent even notices. Killing "search" and "endless feed" entirely rather than trying to tune a filter is the correct call; filters always leak eventually.

A few things I'd want to know as a parent before trusting it: does it embed via the official YouTube API (so ads/age gates still apply) or scrape, and what happens when a curated video gets deleted or age-restricted upstream ? Does the shelf just silently break?