They engineered it properly, which costs a lot. Rabbit R1 was much like how you described; repurposed cheap Android phone with minimal gimmick.
This one looked a lot more lovely thanks to the amount of brain juice spent on it, but otherwise, the end result was ~same.
This is something you can accomplish very easily in a ESP32 form factor, streaming audio over wifi/bluetooth. However, it doesn't fully deliver the same experience; the goal was for it to replace your phone, so it needs to support a lot more functionality such as data persistence, offline support, notifications, cellular, maybe some form of visual IO (the laser projector), etc.
From my perspective I was just interested in the excellent industrial design, which is something that is virtually impossible for a DIY setup to attain.
> From my perspective I was just interested in the excellent industrial design
Debatable. The pin ran hot and had a short battery life, often less than a day even with the extended battery. The magnetic attachment was fiddly to use, and some users had trouble with it not staying put. The laser projector had serious usability problems - it wasn't very bright or clear, and interacting with the projected image (which was required to unlock the device, among other features) was extremely awkward.
One can argue that some of these are implementation issues, but working within the limitations of available technology is an inextricable part of industrial design. Dreaming up a perfect fantasy device is easy; designing one which can actually be implemented is much harder.
What do you mean by 'making this a product?'
Building proofs of concept isn't that hard.
When you need to produce thousands of them, and you've got market/product/engineering requirements, V&V, component sourcing, production tooling to set up, and, importantly, a budget, things get hard (or at least time consuming) quickly.
It's got a nifty laser projector, that's it. It could be a smartphone app.