There are different preparations of monkfruit marketed.
There is the dried raw monkfruit juice, and then there is an extract.
I havent tried either myself, but have researched the nutrition data...
The dried "in the raw" juice or pulp appears to have a good amount of carbs, different brands may vary (check the package carbs/100g) -- but seems you need relatively small amount (compared to cane sugar) to sweeten up a recipe. Not nearly as potent as the extract.
The extract, from what I found, appears very similar to stevia (a few carbs/100g), and you only need a minuscule amount to sweeten a recipe/dish. Again, these can vary... there could be anti-caking additives and such (starch, maltodextrin)... so always check the label nutrition info.
Good luck