The new software also comes with some bug fixes as well as the May security patch.
The phone will be offered for just $169.99 with no annual contract.
The ZUK moniker, however, hasn't completely been dropped, as the Chinese company is marketing the device in India as 'powered by ZUK.'
The listing shows a device carrying a model number of SM-A430U.
Sales start on May 13, but the devices are available for pre-order from today.
The update also brings some WiFi calling-related improvements.
Marshmallow's share was 4.6% last month.
Sony has finally started taking pre-orders for the Xperia X family through its European online stores.
This benchmark listing has also revealed some more specs of the upcoming device.
It's currently rolling out over-the-air to devices in India and the United Arab Emirates.
The information comes from what is purported to be a leaked shot of the phone's internals.
The update also brings along the Android security patch for the month of April.
The Mi Band 2 will have introduce a display, while the Mi Max will flaunt a massive, 6.4" one.
Regarding specs, the Desire 830 sports an Helio X10 chipset with a 1.5GHz octa-core CPU, 3GB of RAM and 32GB of storage.
Also announced is the new Le 1s Eco that comes bundled with the entertainment package.
The standard model, which was announced last month, packs 4GB RAM.
The update weighs in at around 142MB and bumps the software version to G930PVPU2APD3.
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