Recently I built/bought a gyro and accelerometer based head tracker (based on http://edtracker.co.uk).
This device emulates a regular windows joystick when plugged in and, with their firmware, is meant to be used in the game settings directly with no running software and in the ArmA 3 case with the "Look <x> (Analog)" configuration options.
When using the joystick device the resolution is _extremely_ low and choppy. A behavior that is not showing in the other games I've tried.

When using the device along with OpenTrack, or FaceTrackNOIR (with their option to use joystick as input device or load a custom firmware on the EDTracker and use the Hatire plugin written for these Arduino based devices) and presenting the device as either a TrackIR or FreeTrack device it works as intended with very fluid and smooth motions in-game.

According to EDtracker "officials" the EDTracker has about 65000 resolution points from -180 to +180 degrees so there is no lack of resolution presented to the OS, as the other working game also shows and proves.

Using a Cyborg/Saitek F.L.Y. 5 joystick shows the same behavior as using the EDTracker.

Here are some demos;
Using the device native as an EDTracker:
https://www.youtube.com/watch?v=v8QmVRENZns

Used with FTNIR+Hatire:
https://www.youtube.com/watch?v=34JFGDhC2Vo