You can share your internet with your neighbor just make sure to put them on the "Guest wifi" on your router that way it separates them from your internal network.

Heres another added bonus:

Also you can do this, If your router doesn't isolates each device on the same guest network. you can sniff their packet when you want to
If your router does isolate each device. temporally switch the guest wifi ssd/pw with the internal network wifi and then u can sniff their packets