Advise me

What is the key to the success of the operating system? Is it the abundance of models (drivers)? And if I want to make an operating system while I am going to make this system, what is your advice and what is it adopted and what are the disadvantages and dangers that will face me? What I know after the speed and security in the system itself, but the prevalence of the system and its reception by users depends on meeting User needs, and the first of these needs is having complete device models(drivers). A clear and easy way to go into such a large project.

best regards