Sorry I'm not sure I understand exactly what you're asking either. The radio and navigation are independent of each other so you don't need to remove one to install another, if that's what you're asking. The navigation is simply an SD card, all the wiring and hardware is pre-installed.
In Sweden there are three different models. Everyone has a digital display, but the basic model is not equipped with the navigation system, it can be purchased for 800 USD.
The car's manual contains descriptions of various radio systems (A, B, C, D) where type A appears to be an older analogue radio / CD player.
^^Exactly. Select markets get downgraded to no touchscreen so a quick Nav upgrade is impossible. You would need to source the large touchscreen (I imagine its expensive and cheaper to up level to the next trim) and all the associated parts.
I'd do without Nav or use my smartphone if that were the case for me.