FBX import from blender makes models see through

Hi everyone, I like using Blender, but I found that the FBX import on Unity 2020 didn’t like my models.
As shown below the left watering can doesn’t show the faces that overlay on a hollow inside. This keeps happening even when I rotate, also the grey top to bottom parts are not spliced. This leads me to believe that it isn’t a face issue with Blender?

The right can is how it is supposed to look, imported with OBJ. But this doesn;t give me enough customizeability.

The character has the same issue, as you can see. The pants and neck are supposed to not be visible at all (until the payer moves).

I hope you wizards can help me. I am very new with everything so please explain what I need to do like I am 5. Thanks you wonderful people :slight_smile:

Note that the house is not due to these problems, this is just a work in progress :slight_smile: