So far as I know, the dealership battery report is no more than your reading the bars on the display. So worthless.
I paid $8300 for a 2013 'S' LEAF with excellent battery health, back-up camera and QC package* a month ago from a LEAF broker in CA,, and then paid $650 to ship. It still has a couple months of the new car warranty remaining because it was first bought 4/2014, so the 'CPO' option would have been a poor value.
I suggest you persevere with LeafSpy; you have to get it to work anyway
I had trouble getting it to connect my first time too. In my case, I had not turned on Bluetooth (Duh!) and given the phone a chance to 'discover' and authorize the dongle.
*An SL package would also have telematics (smart-phone use) if you pay to upgrade the modem, and a heat pump instead of straight resistance heating as differences for the 2013 MY compared to the car I bought.