Yeah, you are right. Android is a variant of Linux.
Just like MacOS and iPadOS, both run Darwin kernel, but they are very different. Even though iPads have very capable hardware, there are a lot you cannot do on iPadOS.
The same applies to Linux. People want a real desktop operating system.
Unfortunately, when people call their os Linux, they typically are referring to its kernel. I wish there was a better term to distinguish Linux distros from the kernel.
Just like MacOS and iPadOS, both run Darwin kernel, but they are very different. Even though iPads have very capable hardware, there are a lot you cannot do on iPadOS.
The same applies to Linux. People want a real desktop operating system.