Does this result in a function, or does the world-technology continuum collapse?
It opens a black hole that sucks in any technology.
No, probably nothing.
You can access the other's data
Simply connect 1: 1, that will not work. Either nothing happens, or malfunction occurs (bus interference)
it will probably not break…
Nothing.
That depends on exactly which interface the laptops use.
Standard is a host only interface, then nothing works. However, if the laptops are dual-role capable, they can connect via the cable, much like attaching your phone to the laptop. However, I doubt that there are such dual-role enabled ports in the popular laptops and I'm also not sure if the OS would support this feature at all.
USB C Powerdelivery is again something own and although some laptops are able to load from the USB C port devices as well as to be charged.
If such devices are connected, it is usually negotiated who the consumer and who the provider of energy, if this negotiation works, a laptop the other via USB C load.
