I disagree about it being legitimate for games with hard currency. Games do it purely for psychological reasons. They could easily let you earn and spend hard currency in game and spend real money directly. But it’s more profitable to have you buy points.

If Facebook bought one of the big Lemmy instances, yes absolutely, defederate it.

Would be possible to run your own instance from within the app you use to browse? In other words, is there a reason for a personal Lemmy instance, with only me as a user and no communities, to run even when I’m not using it to interact with other communities?

There’s been little demand. Give it some time. Enjoy being in in the ground floor, or wait until it’s a little more mature. The more use and demand the more we’re going to see improvements and alternative mobile apps and such.