wifi:

kábel: TV tuner szükséges
https://prohardver.hu/tema/ket_laptop_monitor_osszekotese/hsz_1-50.html

HDMI to USB Adapter to connect 2 laptops together

https://forums.tomsguide.com/threads/hdmi-to-usb-adapter-to-connect-2-laptops-together.72780/

You’d need some type of video capture(maybe TV tuner) to get the video into the old laptop.