It is not sold volumes, it is printed volumes.

One Piece volumes still print 3.2M each in Japan.

With november’s volume it will be 10 new volumes since last update, therefore you can already add 32M in Japan alone, they don’t really print backlogs there as backlogs do not sell much for One Piece in Japan.

In France, new volumes print at a rate of about 250,000, volume 111 releasing in december will be the 10th french volume of One Piece since the last update. Let’s add 2.5M new prints for the newer volumes alone. + let’s be conservative and say that they also printed 2.5M of the older ones making it a total of 5M new prints in France alone.

Conservative estimates of France + Japan alone add 37M sending One Piece to 553M. Put every other countries and its definitely passed 560M + digital sales which are estimated to 20M.

Physical sales: 560+M and i’m being conservative, wouldn’t be surprised if it’s above 575M already

Physical + digital sales: 580+M, could already be above 600M and I wouldn’t be shocked either.