You can do that quite simply with the normal start/stop circuit used for motors.
https://engineerfix.com/wp-content/uploads/2021/08/Start-stop-circuit.png
You need a NC (normally closed) contacts on both sensors. That is to say that you need sensors that close their contacts when there is no product around them.
The lower sensor will spend most of the time covered in product, so it will usually be open. The upper sensor will spend most of its time exposed, so it will usually be closed.
In the start/stop circuit, the lower sensor is wired as the start button and the upper sensor is wired as the stop button. When the product drops below the lower sensor, the lower sensor contacts close, starting the auger. When the product gets above the uppers sensor, the upper sensor contacts open, stopping the auger. When the product is between the two sensors, the auger won't start or stop.
If your sensors can handle the full current that the auger motor takes, you can wire the motor in parallel with the relay coil. If not, you either need a two-pole relay, with one pole running the start-stop circuit and one running the auger, or you can have two relays with the coils in parallel. Then the contact of one relay will run the start-stop circuit and the contact of the other will run the auger.
You don't need a latching relay. The circuit will latch for you. The only difference is that without a latching relay, when you turn on the power, and the product is above the lower sensor and below the upper sensor, the auger won't start. If you had a latching relay, that could remember over a power loss whether the auger was running or not before the power loss. I doubt that difference would be important to you.