ARM is usually bi-endian, and almost always run in little endian mode. All Apple ARM is LE. Not sure about Android but I’d guess it’s the same. I don’t think I’ve ever seen BE ARM in the wild.

Big endian is as far as I know extinct for larger mainstream CPUs. Power still exists but is on life support. MIPS and Sparc are dead. M68k is dead.

X86 has always been LE. RISC-V is LE.

It’s not an arbitrary choice. Little endian is superior because you can cast between integer types without pointer arithmetic and because manually implemented math ops are faster on account of being linear in memory. It’s counter intuitive but everything is faster and simpler.

Network data and most serialization formats are big endian by convention, a legacy from the early net growing on chips like Sparc and M68k. If it were redone now everything would be LE everywhere.