Pls, check my feedbacks here. Lot of successfulopenwrt projects. For all of them did custom firmware, built from src, for various zbt, tp-link, teltonika, movingcom, mikrotik, xiaomi, open-mesh, gainstrong, and gliNet, of course. Which device exactly are you looking at ?
I also have lot of expirience in parental control, mainly DNS-based, but also based on proxy or using vpn (parental control for mobile devices).