Starting with POWER8, the Linux kernel and some of the BSDs support 64-bit PowerPC in both big- and little-endian modes. Older PowerPC chips had more limited support for little-endian, and all the commercial desktop/server PowerPC OSes that come immediately to mind (classic Mac OS, Mac OS X, NEXTSTEP / OpenStep, OS/400 / IBM i, AIX, BeOS) are big-endian only.

As you'd expect, Linux distribution support for big- and little-endian varies.