FYI, looking at the schematic, there's a diode from the USB connector's power pin to Vin, which is what goes into the PMIC (Vbus pin). The Vusb connector pin is the same as Vin, i.e., it doesn't go through a diode to reach the PMIC (Vbus pin). The schematic doesn't say what kind of diode, but it's not a shottky symbol, so I suspect that explains the 0.5V-0.8V drop observed by @Rftop, specifically between what he labeled as V(PSU) vs V(USB).
Something that strikes me as interesting from the datasheet is:
The bq24195L, bq24195 follows battery charging specification 1.2 (bc1.2) to detect input source through USB D+/D– lines. After the input current limit detection is done, the host can write to REG00[2:0] to change the input current limit.
The interesting part being the "after...". This implies there's a way to override what it detects.
Another option could be to program the D+/D- pins on the nRF to be outputs and to game the detection that way. I believe that would require setting D+ LOW and D- HIGH.
Yet another thing that came up above is the external resistor on the ILIM pin that sets the input current limit. The datasheet says:
The actual input current limit is the lower value between ILIM setting and register setting (REG00[2:0]).
The schematic shows a 333Ohm resistor, which sets a limit of (1V/333Ohm)*530 = 1.6A