I was wondering whether it was technically possible to install wireless connections for WiFi and Bluetooth (f.ex on a raspberry pi 3) before burning the image to the micro SD card. So you would manipulate the (raspbian) image before you insert the SD card into your Pi.
I know it's possible for Wi-Fi. You need to mount the SD card and edit
You should edit the file to look something like this:
auto lo iface lo inet loopback iface eth0 inet dhcp allow-hotplug wlan0 auto wlan0 iface wlan0 inet dhcp wpa-ssid "SSID" wpa-psk "password"
Fill in your SSID and password (keep the quotes!)