Most people believed that updating older device to newest software isn’t always easy, and not just that the worries of device incompatibility might arise after the update, so updating takes resource and time and spend time testing the device for possible bug afterwards.
Sony knows and understand how important updates, but for now, those who have Xperia Z2, Z3 and Z3 compact has the option now to browse on Google Play store and select the desired unit and start testing their device with Marshmallow before the user officially decides to roll over it in air.
But it seems that this option is only available in Netherlands, Spain and Italy to make it clear space is very limited, so in other words you will need to act as fast as you can in order for you to get along. That is only if you live on those mentioned countries as the company releases its app.
So for those who have confusion, the beta testing should not be in partnered with Sony, in short the “Marshmallow Concept” in which the software featured a stock of android experience in order to get feedbacks from its users as its software evolved in states. This beta pre-release of Sony’s OTA update, it needs to be tested first intensively for some bugs officially rolling it out to its designated devices.