I've X4 4.0 from GOG.
I've opentrack 2.3.13
I tried various output options of opentrack available to me and only Joystick emulation yielded a reaction by X4 (alas, not the desired one: Tracking).
I tried -forcehmd.
I understand tracking works only in cockpit.
I understand that Tobi Eyetracker is Windows only.
I'm confused about TrackIR tho, since this has no Windows Only suggestion in the patch notes.
I only find Settings to Enable/Disable Tracking but that's all. This seems to be a QoL key binding only and has nothing to do with configuring an input device.
I can not for my life find out how to get X4 and opentrack talking to each other on Linux. There is an TrackIR.exe and I have an output target for Wine so this _may_ run for Wine/Proton games but that is of no use for the native version of X4 et al, no?

The following Output Devices are available:
* FlightGear (sends tracking data via UDP)
* UDP via Network - basically the same, send the input to a remote service - basically what FreePIE does to turn a mobilephone into a tracking device over wifi but, as long as X4 does not by some miracle understand this and looks for an open UDP port, also not what I am looking for
* libevdev joystick reciever - basically emulates a joystick detected by X4 but that's not a tracking device so has no effect
* Wine -- Windows Layer For Unix - see above - in theory the way to run TrackIR.exe _for Windows games_.
Can someone shed some light on this, please?
Edit: Collected my findings on https://beko.famkos.net/2021/05/03/head ... -on-linux/ (including demo video)