reviews I've seen have been very positive, with the caveat that "out of the box" includes reimaging it with open source firmware. make sure you get a device that can be reimaged this way.
This is a good point. Devices purchased on AliExpress often have their firmware locked. Apparently, it is possible to get around this, but you're better off just getting one that's unlocked from the manufacturer, either via Amazon or the Xteink website,
As far as I understood a locked device can install other firmware if the current firmware supports it. A cooperative flush, so to say. But not an uncooperative one. Fine for using, not good for tinkering.
Correct. We def don't recommend locked users trying to develop on it. Great way to soft brick it and never be able to get back because the USB pins are locked.