LM386 is one of those parts old enough to 1. have a fairly representative schematic in the datasheet already, but even more so, 2. have been decapped and reverse-engineered; you can inspect the physical transistors on die at your leisure.
I don't remember it exactly, but a typical implementation in those days, was lateral PNP current mirrors. The "lateral" detail is important because it's a cheap way to make poor quality PNPs -- hFE is quite low, which has consequences for how the mirror is designed. For sourcing bias current into other (mostly NPN based) circuits, they're perfectly suited.
Related:
http://www.righto.com/2020/06/reverse-engineering-and-comparing-two.htmlI don't actually find a die photo offhand, but this isn't too surprising as the subject is very poorly represented by Google Search.
Tim