I have recently been working on a LAN file sharing site (to upload files from your phone to your computer, vice-verca) but it doesn't work offline as it needs a private IP run on which requires a Wi-Fi network.
So, I was hoping to make a private hotspot (on a computer) via NodeJS which can run the ExpressJS server on.
How do I do this?
Node is not a router, it only receives and parses the traffic it is sent. You're looking to build your own network, what you do with it is up to you.