I can't answer your question, but I can possibly add some understanding.
The problem with designing a NiMH fuel gauge is that those batteries hold a rather steady voltage from 90% full to 20% full. You might do something that calls 1.26V or higher "90%-100%", then 1.25 to 1.22 = 89% to 20% full. The last 20% is when the cell drops from 1.25 to 1.0 volts. Or, you could call anything over 1.24 volts "safe" and start an alarm at 1.2 volts. These are rather crude methods, but they might be sufficient for you.
Another way would involve integrating the current that has been used, but the self discharge rate of the cell would interfere with that, especially in the first 24 hours or if you let the battery sit unused for days at a time.
It is not easy to make a really good fuel gauge for a NiMH battery. and I don't know of a chip to do the job. At best, I can suggest making a less than wonderful gauge.
As usual, anyone else who can contribute is welcome.