Here we see how well the Moto X4 performs over TurboPower based charging when 7% charged using the GRL-USB-PD-A1 analyzer software from Granite River Labs. Once we connect the phone with its own charger, we can see charging happens at around 5 volts as the phone first pulls about 1.6 amps current at power on. When reaching the first 10 seconds, the voltage spikes up to almost 8 volts while the current drops down quickly to near 0.5 amps. As the phone goes into sleep mode, it pulls higher current to eventually charge at around 15.3 watts (5.1 volts @ 3 amps).
Since the Moto X4 doesn't seem to charge well with Qualcomm Quick Charge based charger, it doesn't appear that this implementation of TurboPower is based on Qualcomm Quick Charge. TurboPower also doesn't appear to be USB Power Delivery based since we also see no USB Power Delivery traffic.