Output of the Pixhawk 2.4.8

Hi all. I’m working with Pixhawk 2.4.8. So, from my understanding Pixhawk takes the RC input through the pin RCin, which is read by the px4 firmware, which then calculates the PWM values and outputs them through the TXS0108QFN20 chip. Since, this is an 8-bit I/O chip, I am wondering how is the PWM output value represented by the 8-bits. Also, Is the PWM output in terms of voltage (Amplitude) or Time (Width)? Also, does the 8-bit have anything to do with number of channels? Moreover, I understand that there is a separate PWM signal for each of the motors, how is that differentiated?

Thanks in advance.