When I picked up my 65 plate Leon FR (Tech Pack) 3 weeks ago, the dealer activated Full Link without any charge. I was expecting it not to have the function having read up that Full Link was only introduced to the SEAT range from 2017 onward.
Worked first time after plugging in my iPhone 8. Not even using an official apple lightning cable either..
Actually, full link was there since 2015 and starting from mid 2016 they started to equip it with carplay compatible usb sockets. So my 2015 leon was full link ready, but not CarPlay compatible by it's hardware.