Android - Run an android Virtual Machine on an android phone

You can run Android emulator on an Android phone using VMOS, exactly what you want.

This does not seem to possible, I have looked for it for years and found nothing. This is probably because these points:

1. Android devices have a tiny amount of ram, which cannot be extended. With just 3 GB of RAM, you can forget to run pretty much any VM, as any normal OS needs at least 4 GB by now. A typical PC has 8 GB by now, or even 16. Virtualization is a field where extra ram is especially useful.
2. Pretty all Android devices are based on the ARM CPU architecture. ARM CPUs are very energy efficient, but at the same time pretty weak and feeble compared to full Desktop Grade CPUs from AMD and Intel (which burn a lot more electricity). They don't perform as well doing multitasking, which makes sense: You don't use multitasking much on mobile devices.
3. Virtual Machines are often not full emulation of another CPU, this means that you actually cannot run intel / AMD i386 code on an ARM CPU, so you would need a OS that is especially made for this, i.e. has been compiled for the ARM architecture, that cuts down the selection big time. Debian Linux prides itself on offering the distribution on many CPU architectures, but other manufacturers don't offer that. There is for example no standard full version of Windows 7 or 10 that supports ARM, and neither does Mac OS X.
4. VMs are more of a professional area, while mobile devices are oriented towards non-professional consumers.
5. Disk Storage is another problem: Most mobile devices have very little. A slim Linux can get by with just 4 GB, but a full fledge Linux needs around 10 GB, but a Windows needs around 20 GB just to get going. This is no issue on a laptop or desktop, where you will have 1 terabyte available (1000 GB), but an impossibility if you just have 32 GB.

All these things conspire together to make VMs on Android an impossibility

There's a company called Hypori that already has a virtual android available for both Android and iOS. The only issue is that they only have this available for companies and not for consumer.