Well providing numbers for something that is illegal and happens on shady websites is difficult, just as nobody can tell you exactly how much cocaine enters the port of Rotterdam each year. But I found this to be an interesting read.

https://www.xda-developers.com/piracy-testimonies-causes-and...

I think part of the problem is that whales use Apple.

Despite having 80+% of the market mobile market share, most of these customers are low spending people looking for vfm phones and good enough free apps. Apple is the one that captures the top 5% of customers who spend on subscription services and expensive apps.

This gives the false appearance of Android being piracy heaven. Because, why else would a 4 times bigger consumer base generate a smaller revenue.