I've been experimenting trying to make the perfect pouch for my phone and finally just went back to this simple style. I made one with a box bottom and tried one with darts on the front only, but in the end the extra depth just wasn't necessary and made the sewing far more time consuming and challenging.
This is easy, super fast to make and can be made with scraps of fabric. I'm making another one right now with some scraps from a Japanese fabric from about 6 years ago. It makes me miss some of the amazing fabrics I had back when I started on etsy!
The pouch has a light fleece padding. My phone is already in a rubbery protective thing, so it doesn't need much additional protection, and the fleece just helps the pouch keep its shape.