Yes, EMTEC memory cards are bootable:

1) EMTEC MicroSD or SD cards inserted in a USB card reader can be booted as an EMTEC USB key. See FAQ "Are EMTEC USB keys Bootable?

2) You can also boot directly to an SD or MicroSD card.

Example, on a nano computer like Raspberry PI:

You must download an image (ISO or IMG file) of the OS you want to run from your Raspberry PI. https://www.raspberrypi.com/software/operating-systems/

Then you have to download a utility to install your OS on the Emtec memory card. https://downloads.raspberrypi.org/imager/imager_latest.exe