David, in principle you are right. But take a look at the official web page of Rakuten Kobo for A1-LE:
https://us.kobobooks.com/products/ko...imited-edition . You see there their formal specs description: "32 GB on-board memory, holds up to 28,000 eBooks or 700 graphic novels and manga volumes".
They advertise their product is operational with 28,000 eBooks. They do know how much space the sqlite file takes (750 MB for half of that capacity). And they still advertise the 28,000 eBooks.
I am not opening a debate here. I simply would like to know how I could best use 15,000 ebooks (never mind 28,000 ebooks) on my Kobo A1-LE.