idk if you tried or not but use lile journalctl and see if the logs reveal anything

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/

ubuntu would be fine id imagine Arch is a community project so they cant really stop it and fedora/red hat who knows

this video is great so many people dont consider there threat model and just dive in and struggle and another thing that comes with this is forgetting little things if you look at what gets these digital ghost darkweb admins its almost never intel ME a 0 day in gnupg its always somthing like they said to much and where able to get traced.

Librewolf has been great a lot more privacy and for mobile maybe ironfox has sthing for ios im not sure

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