I would like to be able to display only values over a cut off limit. For example I would like to visualize only data from the Sentinel 5p NO2 where pixel values are greater than a parameter value.
Also, is it possible to have transparency in the resulting image overlay?
You can configure your own product as described here:
See an example of visualization based on various values for NDVI:
You should be able to apply this to S5P data as well.
For transparency check this post: