Keep it offline and don’t update it, Pi-Hole can help, but I wouldn’t count on it. I would also go with NextDNS. Suggest they get a device like an Apple TV and only use that. You can block most of LG’s domains router/DNS side.

If you feel up to it there's the possibility of just lobotomizing the wifi on it. I did this with ours because I wanted to make sure it didn't get any updates after we bought it and it works fine.