Better late than never, or so the saying goes. If one were to apply that principle to the LG G3, the previous generation flagship smartphone from the South Korean conglomerate, then you will be pleased to hear that the Android 6.0 Marshmallow update is set to hit the device some time this month. Originally, it was meant to arrive sometime between the 16th and the 18th of this month, and things do seem to indicate that the Android 6.0 Marshmallow update has passed the testing phase, with LG rolling out the open source code for it, too.
Of course, the update itself has not been released to the masses just yet, but do keep a keen eye out on reports which hail from Poland, as that tends to be the normal market of choice in which LG introduces their very first soak test. Apart from that, it would be the international LG D855 version of the LG G3 that should obtain the Android 6.0 Marshmallow update first, whereas carrier and regional versions could very well receive the update some time later.
As for the current LG G4, that particular model of the flagship smartphone picked up its Android 6.0 Marshmallow update a fortnight ago, with the entire shebang weighing in at a rather massive 1.55GB package.