NewQ Filehub AC750 Travel Router: Portable Hard Drive SD Card Reader & Mini WiFi Range Extender for Travel | Wireless Access External Harddrive & USB Storage Device to Backup Photo & Files from iPhone

So, they make devices that are travel routers and battery banks. https://www.amazon.com/dp/B09T9QKQH7 is an example. You can set up a wifi network on it and just have it running in your bag. This one can also act as a file server.