I think that the problem you run into is that USB isn’t a network of peers. There’s a host, and devices that it talks to. The USB controller circuitry needs to support acting in both device and host mode, and unless something has changed, I don’t think that laptop USB controllers can normally do that.

There are devices with USB controllers that can, like Android devices, which is why you can both plug your phone into a computer as well as attach USB devices to the phone.

I assume that both can handle wireless Ethernet, even if they don’t have wired Ethernet connections. IIRC, there’s an ad-hoc networking mode where one can basically act as a base station for the other. You might look into that. I don’t know what OS you’re using or what support for that is like.

EDIT: I do Linux, but this discusses setup for Windows machines.

https://www.lifewire.com/how-to-set-up-an-ad-hoc-wireless-network-2377459

Once you have them talking to each other via wireless Ethernet, if it’s Windows, there’s a file-sharing feature. If I were doing this between two Linux machines, I’d probably use rsync over ssh.

If you have a base station/wireless access point/broadband router/whatever you want to call it, and you can have both laptops join its network and it can be configured to let both machines see each other, that might cut the ad-hoc network out. I don’t know whether the typical WAP is configured to let devices on the wireless network talk to each other these days, though I suppose that if people have things like printers on their wireless network that have to talk to their computers, they must be.