High accuracy weight / force sensor for the robot flange

Hello, we have a use-case where we would like the robot to monitor the weight of an object it is gripping.

Imagine the robot holding a Bucket and fluids of different viscosities flowing into it. We want to cut off the fluid flow after a certain weight is reached. However, we need an accuracy that is higher than the sensing capabilities of the robot.

Ideally we want to weigh to an accuracy of ±2g (0.07 oz).
Is there a Flange-mounted force/torque sensor that is this accurate?
The highest accuracy I could find is ± 10g (Robotiq FT-300, Nordbo NRS-6050-D80 (PDF datasheets))

Are there other ways of achieving higher accuracy with these sensors (i.e. extending the moment-arm).
For several reasons I want to avoid measuring the fluid flow itself or using an external measuring station. Attaching the weight sensor directly to the robot would make the application as flexible as possible.

Any Ideas would be highly appreciated.
Thank you in advance.