Unifi is great ive and pretty reputable you can do local account etc but if you want a cheaper option and the potential for more privacy id reccomend using openwrt on one of the supported devices you can find info about it here https://openwrt.org/

If your maib concern is soical media / onlinr groups id just say educate them on the dangers not even people but about how the alogrithms they use are built to cause addiction and id also reccomend teaching them basic cybersec stuff like dont click random links how to find scams. etc