That is a monopoly in their own product, not in a market.

In this case, I think it's both. Contrast Android, where other people have set up app stores: https://en.wikipedia.org/wiki/List_of_Android_app_stores

Doesn't matter, Apple is the only supplier of iOS apps and forbids any competition here.

LG is the only supplier of apps for their TVs and forbids any competition there.

So?

So does LG take a 30% rake of all app sales? It's not illegal to have a monopoly. It is illegal to take advantage of that fact with non-competitive pricing.

Exactly.

This poor understanding of what a monopoly is on your part is a testament to how uncommon true monopolies have become thanks to modern regulation.

Time will tell.