Local-First Family Parental-Control Stack That Doesn't Force Apple Family Sharing or Google Family Link Dependency
Cross-platform households (one parent on iPhone, kids on Android tablets, school Chromebook in the mix, Switch and Fire TV on the wifi) cannot use Apple Screen Time and Google Family Link together — the two ecosystems don't talk, and Family Link doesn't even run on parents' iPhones with feature parity. Third-party tools like Qustodio and Boomerang work but are $50-100/year subscriptions that ship traffic through their cloud. Demand is for a Pi-Hole-shaped router-or-NAS appliance that does household-wide DNS filtering, per-device screen-time windows, app-category blocking through DNS, and a parent-phone app that does NOT route through a vendor cloud.
The win is the time-window and per-device reporting overlay on top of DNS. Pi-Hole already does the blocking; nobody has shipped 'kid devices off the wifi between 9pm and 7am, console games allowed Saturday only, parent gets a Slack-able Friday digest.' Don't market it on privacy first... market it on 'Family Link broke for the third time this month' and let privacy be the bonus.
landscape (4 existing solutions)
Big Tech tools are walled-garden-only; cross-platform paid tools are surveillance-shaped. A local-first appliance that works on every device on the wifi (consoles, TVs, tablets, school Chromebook) by living at the network layer, with a non-cloud admin app, is a real gap.