Android Application fundamentals Process Virtual Machine
None of the apps are running in a virtual machine. Really, the page is trying to explain that there's a separate instance of the JVM for each application process. It's quite a misleading description.

FYI, there's no such thing as a "main Linux process". Linux is the kernel, which is not a process; rather, it is above all of the processes, in charge of creating, scheduling, and destroying them, and mediating their access to the hardware.