python - What is the simplest way to get the average of multiple raster images while ignore nodata?

I am looking for the simplest approach to take the average across multiple raster images, which contain a lot of nan values. The mean value should ignore any nan. The gdal_calc does not work, because it outputs nodata when any nodata value is encoutered.

Is there any simple approach with GDAL or python (with any package)? Prefer not to use ArcGIS.