Gaggiuino
gaggiuino.github.ioI'll bring up a cool additional option in this space: https://gaggimate.eu/
Less fully featured, but more open (Gaggiuino became closed source post people profiting off the OSS).
I'll also pitch another fun OSS project I sponsored a few years back to build an OSS pressure sensor and 0.1g scale: https://github.com/rhit-coultabm/Consistent-Cups-Espresso-Ac...
Since then it looks like Decent has OSS'ed the DecentScale: https://github.com/decentespresso/openscale
I upgraded my GCP with a PID kit I bought from a UK vendor that changes the analogue temperature readings to digital along with the 9 bar OPV mod to bring the pressure of the brew head down.
This project goes a lot further and I would love to do it one day.
I've been watching Craigslist prices for Gaggia Classics for over a year just for this. Now if only I had the counter space for the build in addition to my DF64 and Flare 58!