For anyone interested in this sort of thing (like me), the Decent DE1 Espresso machine is a well-engineered, cafe quality, open-source machine that you can buy.

There is a small community working on various software apps around it. The machine is controlled through open BLE comms. All the control software AFAIK is OSS and tinkerable. The machine itself is top notch, and in my espresso-nerd opinion, beats anything on the market except in appearance and "analogeness".

So if you like espresso and hacking on software, check it out.