Yep, Jio launched their network in 2016ish, and didn't get many IPv4 addresses (probably didn't want to spend the significant amount of money to aquire addresses, maybe couldn't find large enough blocks for sale), as a result they require their branded devices to work with IPv6 and pressure their partners to do IPv6 as well.

I have no stats, but I wouldn't be surprised if it was the largest single action driving v6 adoption ever.