@LukasPsy Get in contact via e-mail: it might be a while before I can get these into a more portable/generalisable form for hosting on GitHub, but happy to send you our module files as they currently exist and hopefully you can modify them for your own ends.
You can also control SMI eyetrackers via serial, unless things have changed in the past few years. The protocol is real simple.
FWIW we’ve done calibration outside of our tasks with WinCal; we just never found there was enough benefit to building calibration into our tasks.
UDP has the advantage that messages are received complete, in a single packet. I found when I initially tried using the serial connection (which I assumed would be easier) the complication that you could often collect just the first fragment of a message and then have to construct the full message by concatenating fragments on successive checks. This adds a degree of complexity that UDP messaging avoids, because it returns complete packets rather than being a stream that you can end up interrupting mid-message.
But perhaps the real advantage of UDP is that all computers and operating systems can use it: you don’t need a serial port or some sort of USB serial emulator, and there are no Mac vs Windows/Linux restrictions.