Jio is fascinating. I once held a talk at an event where their Interim CISO Karsten Nohl was also speaking.
The way Jio was built and what challenges they faced trying to build a gigantic mobile operator from scratch and building it secure from day one are a story i'd like to read a book about, but I'm already glad he held a talk about it.
The most interesting part was their realization that there was nearly no "new & secure" hardware available they could buy off the shelf, most came with old unpatched versions of software, many had components that simply had no update functionality at all, some had but required manual onsite intervention for updates, just what you need when you want to connect one of the largest countries on this planet. This was not third-rate stuff from China, he was talking Ericsson, Nokia, Huawei... the name brands involved in this space.
Fascinating and astounding what went on at this time at Jio and i'm grateful that sometimes people that deeply care about these issues get into these positions and get to fight these demons.