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 to and from those devices 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.
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
Many people use WiFi to connect to their printers for the sake of convenience
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 to and from those devices 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.
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