Custom Oak Cycles 650B French Randonneur Project.

Depends how you measure it, of course. A Pearl 10 is 10cm if you measure it as though it were a 0° stem, 11cm if you measure it along the top, as a -17°.

Precisely, they also have a clear diagram on their box showing exactly that.

Still, not sure if there's other manufacturer who measured it just as Nitto does.

Are Ryan's stems good?
Did Ryan used to work at Brixton Cycles?

I've seen his recent work and was impressed if a little flummoxed by the purpose of such set-up;

As for Brixton Cycles, no idea.