In this U11 teardown you can see a chip marked “T44 AHB”. That should be an Atmel ATtiny44A.
It has a different footprint than the Attiny25/45/85s usually used here.
If you find a way to connect the required pins (a four-sides QFN/MLF/VQFN clip if it exists may work or not) it should be as programmable as the other microcontrollers. (I guess the chip is programmed before soldered to the board.)
You just have to reverse engineer what pin does what to adjust your firmware of choice accordingly.