Reliance in India basically ran a severe loss for Jio (their new mobile network where they essentially gave the country free mobile internet), but paid for by the profits of their fossil fuel business.

For a while, didn't Amazon do the same? They basically ran a loss with Amazon retail but profits on AWS, until they spun off?

So yes, this is fairly common with conglomerates, (Amazon sold diapers at a loss to put diapers.com out of business). And in fact, this tactic is a target for anti-trust laws where they exist.