You can have devices on your wifi network without giving them access to the internet. You set your firewall (which, for most people, is the router that comes with the internet subscription) to block all internet traffic while still allowing them to communicate with the other devices on the same local network. Fairly straightforward on most routers with a little bit of time spent looking up the basics.
elvith@feddit.org 5 days ago
Exactly what I meant with
Most routers allow you to set child safety settings for devices to block them from accessing the internet in specific timeframes or completely. You can still access the local network from the affected device or access that device from your local network