Embedded Linux devices come in many different sizes and varieties. Some may have app stores, but most don't. There are various methods to get the OS and apps on the devices.
Embedded Linux
OS deployment
The deployment of the operating system will on your device, as some embedded devices have very specific methods in which the operating system is deployed to the device. In the case of Raspberry Pi, it is easy to copy the image to an SD card and put that into the RPI and boot it up.
I have a script named writeIso that I use; it consists of two lines:
#!/bin/bash
sudo dd if=$1 of=$2 bs=4M status=progress
I run it something like this:
./writeIso /path/to/deviceImage.img /dev/sdc
Other devices may have a flash method, whereby...