Okay, we’re coming clean. [Design Build Destroy] didn’t add memory to its Arduino Nano. But compared to the standard setup, it has about 1.5 K more program space. The trick? On some nano boards and clones, the bootloader is set to use a large block of reserved memory, but Optiboot only takes up a fraction of that reserved memory. You can reclaim this unused memory by reprogramming the boot loader and changing the configuration backups.
Of course, you can’t just overwrite the bootloader and backups through the serial port to prevent bricking your device. The video below shows how to connect another Arduino to do the programming. You can also use any dedicated AVR programmer you happen to have. Oddly enough, the Uno is already using Optiboot with the same processors and is set correctly and the video shows the differences in configuration between the two in the default state.
Of course, depending on where you get your nano devices and how old you are, you’ve already set up this facility which is nothing to gain from, but you should be able to easily tell whether or not you need to go through the steps. The same trick will likely work with any older Arduino boards you have lying around if Optiboot supports them. What can you do with the additional storage? Maybe speech recognition?