>Microsoft stipulates that other OSes need to be able to run on these devices. However to do so one has to obtain a boot key from microsoft.
No, Microsoft stipulates that the secure boot should be able to be disabled without needing to obtain a boot key from Microsoft. In fact you can install your own personal key and remove Microsoft's to prevent Windows from booting.
>The implementation of secure boot on some devices is hardcoded to windows and won't work otherwise
Reference?
>Dell/HP/Asus etc. are monopoly holders to personal computing hardware
If there are multiple companies in the market with comparable market share, by definition they are not monopolies.
>Microsoft stipulates that other OSes need to be able to run on these devices. However to do so one has to obtain a boot key from microsoft.
No, Microsoft stipulates that the secure boot should be able to be disabled without needing to obtain a boot key from Microsoft. In fact you can install your own personal key and remove Microsoft's to prevent Windows from booting.
>The implementation of secure boot on some devices is hardcoded to windows and won't work otherwise
Reference?
>Dell/HP/Asus etc. are monopoly holders to personal computing hardware
If there are multiple companies in the market with comparable market share, by definition they are not monopolies.