Windows Phone was the complete opposite of Windows. Manufacturers couldn’t configure anything to their liking other than preinstalling a few apps. No UI changes, very little branding, and the apps themselves were sandboxed in ways that protected users instead of enabling manufacturers.
The result was a lack of manufacturers who wanted to play ball and risk releasing devices. This wasn’t exclusively responsible for the failure, but it helped continue the vicious circle of no devices, so no customers, so no apps, and so on.
As someone who works for Microsoft I can say pretty authoritatively that calls with manufacturers and carriers were rife with feature requests and demands before they’d consider making devices available to customers. Something they didn’t need to deal with on Android because the OS is open enough for them to build it themselves without Google’s approval.
Don’t get me wrong - it all results in a worse experience for customers, but manufacturers and carriers didn’t want another iPhone on their hands dictating things to them.