So the promised article finally materialized...
...shame about the circumstances :/.
Since that wasn't elaborated on in the text, the keyboard mod was called Livermorium. As you can see, it was a horizontal slide-out physical keyboard, which, AFAIK, is an object of great desire of many commentards in these trying phablet times.
Sadly, supposedly due to fabber shenanigans and lack of support from Moto, the project was ultimately cancelled, with only a part of the original backer order shipped.
The team behind it went on to working on a dedicated slide-out modern Android phone. Backers for Livermorium who haven't received their unit had the option to either get a full refund or get credit towards the new phone.
Overall, somewhat of a sad story, and it would be interesting to hear how it went from the Moto side of things.