If this was half the price, I might be interested. But if I wanted a coffee maker with open source control, I'd probably just hack an existing cheaper product. And I'm someone who absolutely loves assembling stuff from kits!
Heck, I'd be surprised if someone hasn't already got Doom running on a Sage.
Exactly. The parent post mentions this being "the wrong solution to the problem", but I don't know what the problem is this product is addressing. E61 machines are well understood and diagrammed with (somewhat) interchangeable parts. If this product appeals to you, you can buy a cheaper/similarly priced machine, take it apart and put it back together yourself.
* Espresso machine electronics are very proprietary. There's basically one manufacturer, no published schematics and very closed firmwares.
* That one manufacturer's hardware occasionally breaks and needs replacement, and they charge up the wazoo for it.
* Firmware updates is not a thing. Buying a new controller with the new firmware is your only option.
* Espresso machine electronics hardware is pretty firmly stuck in the past. If you're lucky you have a 128x64 px OLED, but more likely you have LED indicators, 7 segment displays, or graphical LCDs.
There are absolutely exceptions to this, but for 95% of the espresso machines out there, you're definitely not getting the full potential of the hardware.
Perhaps you're thinking of the commercial market and I'm thinking of consumer, but there's been a lot of really interesting developments in the last few years at the intersection of affordable and high quality output -- I own a plus Bambino plus now, for example, which is simply a delightful machine, though I too wish I could modify the firmware.
More control than that, or a totally open PID, might be a hard sell for safety reasons. That alone is a nonstarter, but even as you approach that level of openness, it would be pretty hard to support and really isn't needed if you just want a good shot of espresso and aren't taking an niche academic approach to an already niche process. This is why you likely won't see it in more commercial machines.
I don't know if I'd consider adding a screen to an espresso machine to be an improvement. What would it be useful for?
(1) Automatic shot timer.
(2) Shot volume display (my machine is a volumetric one, but I have to measure the weight of the output to calculate what volume it dispensed)
(3) Ability to configure other parameters, such as pre-infusion time, where I'm guessing the manufacturer just left this out because it would complicate an already kind of painful button + LED UI.
I also wish it had a group head temperature sensor, but that would add more hardware to the machine than just the screen.
I've ordered DIY framework laptop not because it was cheaper, but because it was fun to build it.