In fact, Power ISA is probably the last architecture where both modes still have notable importance: AIX, IBM i and OpenBSD still run Power big, FreeBSD runs it

In fact, Power ISA is probably the last architecture where both modes still have notable importance: AIX, IBM i and OpenBSD still run Power big, FreeBSD runs it big but work exists to run it little, and most Linux distros run it little (not counting 32-bit PowerPC, which pretty much always ran big). Most of the other notionally bi-endian architectures nowadays have settled on one. For example, SPARC is just about exclusively big; conversely, ARM64 got rid of their big-endian mode.