When reflection light is absent, this channel is limited by the circuit noise which is slightly larger than the ADC noise.
In the case reflection light is presence, K1:ALS-X_ARM_REFL_IN1 which is raw ADC count shows ~6.4ct = 3.9mV.
Universal whitening filter is now set as 12dB gain at DC. So the PD output should be 1mV (at differential) and 500uV (at single-end).
Considering 100Ohm as an impedance and 0.3A/W as a PD efficiency, the laser power at RFDC is ~16uW.
