Regarding sales, I've always figured it's a good indication of how many devices there are if you count the downloads from the Jolla store. Android compatilibity is the most downloaded app and it has currently a bit over 12,000 downloads.

I believe it counts downloads per user (a Jolla account), otherwise if you were a developer of course you would make a bot to download it a thousands times a day to keep it on top of the lists.

So 12k to 15k is a good estimate of sold Jollas.