While the goal is noble, it is patently a boondoggle. DRDO is setting up TWO software engineering centers to write this one operating system. Its waste is evident when you think: MIT computer science students used to write an operating system for their 6.033 design project [not sure if they still do that.] Linus Torvald largely wrote the Linux kernel on his own, over a 4 month period. [Other people contributed codes for features later on, but Torvald finished the functional prototype.]
The Linux example stands out particularly, because it is open and already working. China's software institute, for example, has customized a couple versions of Linux for domestic use. If India cares about developing a useable product and plugging security holes, it should deploy a suitable Linux version immediately, instead of putzing around with an ego project/pork like this operating system project.
That India is continuing with Windows while waiting for DRDO, with its long history of over-budget and over-schedule projects, means that this stunt was for political purposes rather than to satisfy a present capability gap. For most computing needs, there are open software products available.