Build a new operating system, or build an operating environment that runs on top of an existing operating system, like how e.g. Windows used to run on top of DOS? Or User Mode Linux on top of Linux?
An operating environment means you don't have to worry about stuff like device drivers. It can run inside a Docker container. (At most companies, try suggesting "let's run a brand-new OS that nobody has heard of", and you'll get an emphatic "no"... say "here's this app we want to run, it is packaged as a Docker container", and often nobody will even ask what is inside that Docker container, even if it contains your operating environment with the app running on top.)
You can start out using facilities of the host OS like the filesystem and networking stack. Later, if you want to, you can implement your own filesystem (create a 100GB file on the host filesystem, pretend that is a block device and your custom filesystem exists within it). Or your own networking stack (which can run in user space using facilities like Linux tun/tap drivers.)
An operating environment can always evolve into a standalone operating system at a later date.
An operating environment means you don't have to worry about stuff like device drivers. It can run inside a Docker container. (At most companies, try suggesting "let's run a brand-new OS that nobody has heard of", and you'll get an emphatic "no"... say "here's this app we want to run, it is packaged as a Docker container", and often nobody will even ask what is inside that Docker container, even if it contains your operating environment with the app running on top.)
You can start out using facilities of the host OS like the filesystem and networking stack. Later, if you want to, you can implement your own filesystem (create a 100GB file on the host filesystem, pretend that is a block device and your custom filesystem exists within it). Or your own networking stack (which can run in user space using facilities like Linux tun/tap drivers.)
An operating environment can always evolve into a standalone operating system at a later date.