And regarding unlocking some additional LTE bands I also have read about some tools for Qualcomm and Mediatek based devices.
The threads on XDA are showing up under the "mediatek lte xda" or "qualcomm lte xda" queries to Google.
Although, like previously, I haven't tested it out on my own.

Of course if there is no support for 4G/LTE at all in the hardware, then there would not be possible to enable that (like said previously).