I believe the oil filters from the tundra/sequoia/4runner all will fit the GX since the engine is the same. In fact, I run the landcruiser/LX470 oil filter, which is made by Denso in Japan, in an old 4runner.
The parts guy at American Toyota in Albuquerque, who's a cruiser buff, told me the media inside the Japanese-made Denso filter is superior (resin core) to the cheaper filter that comes in Tundras/Sequoias (and probably 4Runners). The list price is like $15 vs $5 (these were Toyota USA prices, not Lexus prices; so you really do get better quality parts in Lexus and the top-line Toyota [landcruiser] vehicles

). It's really using the Denso filter that Toyota based their 7.5K mile oil change intervals on, so I hear. The Denso filter also has a pre-lubed gasket (has a piece of plastic protecting it, gasket is red color). The bad news is, Toyota USA no longer stocks the Denso filter, but I believe you can still buy through through Lexus.

A number of 4x4 toyota guys (including myself) have stocked up on the good Denso filters before they were discontinued. You can still buy them in Japan, but they cost 2000 yen ($18) each. The replacement filter (looks the same from the outside, but no pre-lubed gasket) is made in Thailand. If you plan to keep the vehicle for a while, the best thing you can do is to run the Denso filter and a top-quality synthetic oil (like Mobil 1 0w40 [ACEA-3 appproved and factory fill for Benz/BMW while Mobil 1 5w30/10w30/15w40 is only ACEA-1 approved for GM]), Mobil 1 Delvac 5w40).
In fact, some toyota dealers will work on common Lexus vehicles (LX450/470, etc.), while others refuse to. In Japan, the GX470 is the Landcruiser Prado w/ a slightly different front fender/grill, 4Runner is the hilux surf (built in the same Tahara factory), LX470 is the Landcruiser "Cygnus" (higher-grade LC), Landcruiser is the "Landcruiser 100." Also, overseas, the Prado/Surf are only available w/ the 3.4L 180 hp V6 engine (found in the previous 4runner), 2.7L 150 hp 4-cylinder, or the 3.0L 180hp turbo diesel...the V8 is a North America-only thing in the prado/surf platform.