@ Duke Nukem - How timely! I am starting a new Gadgeteer module that has an SpO2 sensor similar in size to what is used in all the wearables (e.g. watches).
Roger, thank you for your offer to let me help, but I am no longer interested in doing anything with commercial medical products. What I did was for my own use only and I would not be available for any help getting a medical product to market for many reasons. I wish you the best of luck. I am sure you will find many developers here to assist you in many ways.
However, I don’t think GHI sells the Pulse Oximeter module anymore.