GBIF currently does not have guidelines for publishing satellite occurrence data, but I will do my best to answer your questions below.
Has anyone published satellite species observations to GBIF?
Yes! Some publishers have published satellite based occurrence datasets: Search (The link referred to migratory datasets using GPS location tracking. Not relevant for satellite image-based occurrences.)
Given that data shared to GBIF is tabular, should it be converted to polygons and a footprintWKT created for each polygon?
As I mentioned, there is not really any standard for how such data should be shared with GBIF, but perhaps you can find inspiration here and other parts of the guide may be relevant to you as well.
One option could be, for each occurrence record, to provide both a footprintWKT for the entire polygon, a centroid of the polygon as
decimalLongitude and coordinate uncertainty. How large are the pixels you refer to? I guess it is satellite system dependent? I still need to mull over the idea of using each pixel as a basis of the occurrence and would like to know how many pixels on average are in a polygon for example. But it may be the most detailed way to share the data (and use the data as well).
Are GBIF users using footprintWKT for analyses? Is it easy for users to work with?
I will answer these two in one go. We do not know if users use footprintWKTs for analysis. This might be possible to find out through a literature search, but @dnoesgaard probably knows better than me whether it is possible.
Working with footprints require some technical spatial/GIS skills and my understanding is that most people rather deal with coordinates and the uncertainties associated with the coordinates. But for the technically proficient users, I think footprints could potentially be very useful and perhaps we will be able to visualise them in the portal with the new data model.
We are waiting for them to finalize their database and then hopefully publish a dataset. Happy to share our process with you once we have that published.
Thank you - we would love to hear more of your process! It is some very relevant questions you pose since we see more and more of these satellite-based monitoring efforts across the world. I would also be very interested to hear how certain the identification of the different species is - it is my understanding that it can be challenging to differentiate between e.g. a rock bed and seagrass, especially with high turbidity etc.
I hope this answers your questions but let us know if you if you have any follow up question.