These things do exist in theory - for example https://m.alibaba.com/product/60020735464/Protable-1000M-hub-2-0-print.html?spm=a2706.7843667.1998817009.6.AQcVLj#show_specifications- but they seem to overwhelmingly be unpolished junk. You might get lucky though. As far as powering them, as this uses 5v, 2 amps, you could use a USB power bank - and 3d print a case if necessary.
Half a step up might be http://www.silexamerica.com/products/connectivity-solutions/device-networking/usb-parallel-connectivity/ds-600/ - but as it requires 12 volts you would need a more sophisticated power bank. They do exist (I have one) but are clunkier, bigger and harder to find. Look at stores that sell car accessories - these things are sometimes sold as jump starters.
Lastly I found https://www.eltima.com/usb-over-wifi/ but It's short on price and specs.