Love this project! That line about unintentionally teaching kids to consume music passively really resonates. I built something with a similar motivation – Muky ( https://muky.app ), an app for creating curated, distraction-free music experiences for kids. Different approach (digital vs. physical), but the same core idea: helping kids engage with music intentionally rather than as background noise.
I'm not in the target market for this, but I've heard other parents wish for a way to curate their kids' YouTube experience. For example restricting them to certain pre-approved channels. I wonder if there's a clever way to do that with a companion app, like you've done with Muky/Spotify.