I've so far only flown in Europe thus was never able to test the obstacle feature in the G1000. It is my understanding, that they only show in the US because they are free of charge.
Today Austrocontrol, Austria's (ICAO LOxx / OE-) ANSP, released .kmz files for LOWW, LOWS and LOWG for free via this link: https://bit.ly/2Eto1w3 (sorry, I had to shorten it and it's only in German). It does say in the disclaimer that commercial usage is forbidden but what I'm wondering is, whether it's possible for the individual to add obstacles from a file like .kmz privately and thus not violate the terms and agreements.