I already find the wifi range on Jio router to be worse than previous adsl airtel router. That seems highly unlikely. However the part about Jio controlling your router is true. You can change SSID and password of jio router using my jio app and block devices in real time even on any other network with internet access. They also have MAC address and name of every device that you ever connect to network.
Regarding the isp being able to control/change customers CPE settings has always been there. Even MTNL could do that & they did like changing DNS enterirs etc. Whether they can make ur router into a hotspot is debatable. They will probably require ur permission.