Is there any device such as a typewriter or keyboard that is portable and can save data to a USB (other than a cell phone or smarthphone )
This is EE.SE. So in that vein I'll toss out another idea. You might look for something called a Mailstation. There are a number of closely related incarnations of it, but all of them basically amount to a keyboard with a small, built in monochrome LCD display. It runs off of AA batteries for quite some time, is easy to use, very very light weight, and is practically free if you can still find someone wanting to get rid of one.

However, it does NOT have a USB connection. You can add one with a microcontroller, some circuitry, and some software. I know this works because I've already designed the schematics, wired up the circuit, programmed the micro, and have a small box I use in conjunction with my own Mailstation to connect to any PC USB port and transfer the text files from the Mailstation to the PC, with ease. I use its printer port, capturing the data as it is transmitted, and then pass it along to the PC via a virtual COM port created via a standard USB HID driver which you do not need to bother installing under Windows, since it already exists in all installations. I use the "print" command as a way of transferring any selected text file. So it's another possible route. But it's not a commercial, off the shelf solution, if that's your goal.