Do you choose your block size when you use dd? For me, on multiple OSes and oldish hardware,
$ dd if=/path/to/iso of=/path/to/disk bs=1M
seems noticably faster than etcher. I suspect thats not even the optimal choice
Edit:noticed this is sort of a repeat answer, leaving it so the people saying its slow can copy/paste and try it out.
I think what people are complaining about is the fact that the linked project is not the project that actually solves the problem stated in the title. This linked project did not enable “using a raspberry pi as an airplay server,” it just packaged someone’s project that already did that.
from what i can tell, the pro version is fairly hackable - you can literally write software that will sense what's plugged into it and do something with that. for example, you can plug an oscilloscope into port 1, a DMM into port 2, a 3d printer into port 3, power your circuit from port 4, and you have a "brain" that controls your entire setup as well as reads inputs from your measuring equipment, might be far-fetched, i'm just spitballing ideas here
calculating how many times a person clicks "download" on their website times a guesstiamted number of cards a person would also give a good enough estimate without any telemetry