I hadn't intended to drive till the light came on, but it did tonight. The "Estimated Distance To Empty" read 25 when the light came on. The manual says the light comes on at 1.7 gallons remaining, but elsewhere says the ICE may not start if there is less than 2 gallons, so not sure how far if any I can drive in HV mode tomorrow. 1.7 gallons should be good for about 75 miles, but the DTE estimate was 25, so there might be 50 miles after DTE of 0 as long as you don't shut off the car?
You have a Gen 5 but in my Gen4 Prime, I can go about 30-35 miles after the DTE turned to "--". of course your mileage may vary. Just dont run out of gas; it's very hard on the HV battery to try to start a engine that wont b/c of no fuel further draining your EV range and leaving you stranded.
That occurs in the "Running out of fuel" section. My reading of that is that it's talking about how to get it started again in that situation - if it has actually run out of fuel, you may need to add 2 gallons, rather than a tiny drop. I imagine that's because it's not going to re-attempt the engine startup after fuel exhaustion until the fuel sensor clearly indicates available fuel.