I totally get what OP is asking and am constantly annoyed by the same thing.
There's a ton of software that can ONLY be run on a mobile OS, and rather than deal with the nightmare that is a physical Android phone with all of its limitations and restrictions, it would be nice to have these things running in a VM that I can fully control. There's software that demands access to insane and ridiculous permissions, and I'm not going to install those to my physical Android phone and deal with the privacy problems. But a completely isolated VM with burner accounts that I can run in a window on the desktop I'm already using most of the time anyway? I'll take that. Also, I don't see the need to shell out the ridiculous price premiums for phone models with the most storage space when I only use a handful of apps when I'm mobile anyway. An app I might need two or three times a year still takes up that space on my phone when it could easily live on a VM and be used only when I need it at home.
Also, when Android releases new version updates and my phone manufacturer doesn't keep up? Why should I have to go out and buy a new phone just to appease the handful of apps that decide THEY want to be cutting edge and THEY'RE going to be the ones to force me to waste money? I should be able to just spin up another VM with the new Android version and use those sporadic apps on there until I decide to upgrade my phone in my own good time.
Also, Android X86 is fine, but the most problematic apps that mess with users and force apps to newer Android versions for no other reason than being "cutting-edge" aren't made by the kinds of companies with the forethought or customer focus to provide x86 compatible apks.
Basically, I don't see why it's so hard to run a full virtual, sandboxed ARM emulated vanilla Android environment, or why people aren't clamoring for this. It's the most practical, straightforward solution to the fragmentation/bad vendor update model that physical hardware forces on us and I assume most of us hate.