This Python script converts an entire directory containing nef images to jpg.
To install the requirements using pip:
cd photoconverter
pip install -r requirements.txt
In the script, be sure to change '/path/to' to the absolute path of the folder where the images are located.
Here are a few estimated times depending on your number of images.
If the program is interrupted, don't worry. While you'll have to run it from the beginning again, it will simply overwrite the new images already processed. It won't make any duplicates.
Your original files will remain and the quality will not change. No previous data will be deleted or overwritten by using this program.
I will try to include a few sample images that I find online here as well :)