Testing if you're running under virtualization or emulation is a whole thing. We wrote virt-what to do this for virt and containers. It could do emulators as well if someone was motivated enough. It's basically a giant shell script. https://people.redhat.com/~rjones/virt-what/

There's also an adversarial aspect to this. Some emulators try to avoid detection and a lot of software tries to detect if it's running under virt for various reasons, eg. to stop cheating in games or stop reverse-engineering. (virt-what is deliberately not adversarial, it's very easy to "trick" it if you wanted to do that)