Can I extend the green led on the pi 3 by soldering wire and led from the same spot or do I still need to add a diode or something? Sorry for the noob question
If you have to ask this question you almost certainly do not have the tools to perform this task, which would be a bad idea. Putting LEDS in parallel seldom works, and it would be a difficult task.
Instead I suggest you use a LED connected to a GPIO.
Name: pi3-act-led Info: Pi3 uses a GPIO expander to drive the LEDs which can only be accessed from the VPU. There is a special driver for this with a separate DT node, which has the unfortunate consequence of breaking the act_led_gpio and act_led_activelow dtparams. This overlay changes the GPIO controller back to the standard one and restores the dtparams. Load: dtoverlay=pi3-act-led,<param>=<val> Params: activelow Set to "on" to invert the sense of the LED (default "off") gpio Set which GPIO to use for the activity LED (in case you want to connect it to an external device) REQUIRED