Well, there are a few ISAs (Instruction Set Architectures) supported by Android. They are armv8 (aarch64 or arm64), armv7 (armhf), and x86_64 (amd64).
Every SoC does not have a completely different instruction set. Whatever you read has no idea what they're talking about I guess, or you did not understand it properly. We also do not use VMs or ART for the Android portions we need.