Why We Don't Have PPP in Defense Sector?

Hi Lovely People, I always think why don't India have a Public Private Partnership in Defense. I mean the best engineers in anywhere in the world are Indians, the most numbers of PhD in stem is hold by Indians, they are great in AI then what's stopping us. Is it the bureaucracy or is it like National Intelligence matter. I mean in Space we have new startups who are giving tough competition to ISRO and are someone who are making ISRO to always stay on Top. But I don't think any competition of HAL is their. Why is it so? Why can't we have tech startups who can actually create aircrafts for Indian Army? If their is any Defence Expert I would love to listen to their views and any suggestions how we can break the monopoly of old ass Govt Organization.