Hi, I'm extremely new to growing any type of plants, but I decided to put down a few pomegranate seeds during spring, and managed to not kill them throughout the summer. My worry is, however, that I have somehow not supported their growth properly or that something has gone wrong, since for example one of the sapling is now 70 cm long, with a stalk width of less than a cm, no branches and naturally looking more like a vine than a tree. Have I done something wrong? The other saplings have not been as prolific in their stalk growth, but given this example individual I can't help but to worry

Pomegranates are naturally a little floppy tall shrubs but yours are overly floppy. They need fall sun.

Hi & welcome! That is cute, even if it's not upright!

It looks a lot more sunny closer to the window. So bright that I can't see if there is room to move the plant over where the sun can shine right on the leaves when it is on that side of the building. You could use some kind of stake. If trying to grow inside is your only option for this plant, I would encourage you to investigate different types of supports and pruning techniques, like espalier, to guide your plant to make the most of the light by the window. IDK if that will be enough for it to bloom and make fruit, but if that is what you have to offer, it doesn't hurt to try.