Illia

I'd say go more with Mahoi than Gran Nain, but Dwarf Cavendish is a good idea too. There's actually someone online here who has a D. Cavendish that is fruiting indoors right now. They had to chop the plant back a couple times though. Just remember - Bananas like LOTS of light. As much as you can give them when it comes to growing indoors.

Also, as mentioned earlier, Dwarf Red isn't a bad idea either. Especially considering you will be growing something that doesn't taste so similar to the storebought Gran Nains. (cavendish type in general)