How to create a flash drive image manually (not a dump)?

Question

Disk image

There is some data that needs to be written to flash drives. The data is only somewhere around 2-3 GB, but the problem is that they consist of small files of 10-15 kb each. The number of files reaches 50-60 thousand, copying takes many hours.
There was an idea to roll the finished image, it takes much less time. But writing everything to a USB flash drive, then dumping it is not an option, since this data set is needed in just one copy.
Is there software (win, linux) that would allow you to create a virtual image of the drive, write files to it, and then roll this whole thing onto real hardware?

Answer 1

For Linux:
1. Create a file of the required size:
2. Create a file system inside the file:
3. Mount (ideally somewhere on a ramdisk)
4. Copy what you need, unmount.
5. We write the image to the section on the flash drive
Item 5 has not yet been tried (there is no experimental flash drive at hand), but in theory everything is correct.