I have a Toshiba Canvio AeroCast 1TB Wireless Portable Hard Drive USB 3.0.
This has an internal battery that will run the drive for around 5 hours. It can be used as a normal external USB 3.0 drive powered (and charged) through the USB connection, or, when running on its battery, it can be accessed by WiFi as another client on an existing WiFi network. However, it can also provide a WiFi hotspot to which clients can connect directly. In this mode, the drive can attach to an existing WiFi network and then support a number of devices on its hotspot, in much the same way as a Windows 10 laptop can connect to a WiFi network and then provide a hotspot for other devices to connect to.
When my drive has its hotspot enabled, it is a battery powered WiFi router with an integrated disk drive. At 8.6 x 12.4 x 2 cm it is around the size of a 3.5" disk drive, so it is rather larger than a normal external portable disk drive, but in addition to its battery and routing function it also has an SD card slot, which will automatically back up photos, etc from an SD card used by a digital camera.
So, the answer to the question is YES. I have one made by Toshiba that also has 1 TB of on board storage.