The sunshine sensor is basically 8 photodiodes (for the radiometry part, otherwise it also has plenty of other functions) which are linear with irradiance as it has already been stated on this forum. The data can be extracted from the tags of the images (as already explained). No need for additionnal software.
We are not Pix4D. We can't provide you something we don't have. Yes Pix4D is a subsidiary of the Parrot group, just like Parrot Drones which is manufacturing the Sequoia camera. These are two separate activities. We can provide (and we will) information about how to calibrate and correct your data. We can't do it for you.
We are sorry about the problems of communication in the past and believe me we are doing everything we can to make this right.
All the companies you are citing here helped develop the camera, we are not giving them competitive advantages, they just developed the camera
@kikislater I sent you a private message about that claim. I don't know which dataset you are referring to. I've checked online and can't find datasets with irradiance values stored in exif. If this is the case, then this dataset is not up-to-date. BASE64 is a well-spread binary to text encoding scheme and the detail on how to extract the data has been shared publicly on this forum.
@kikislater I also answered on this point by private message. Could you tell me where you bought your camera? In the case of Sequoia, the SN shown on the packaging must have the format PF740000****** ****. The camera itself and the sunshine sensor each have an identification number in the format PI040379****** **** (sunshine) PI040378****** **** (camera) plus an additional number PS740000****** **** for the camera. So I understand that problems can happen if the distributor is not careful enough. I hope that it is the number PS740000********** that is indicated on your order.