Manufacturers don’t make displays under 6 inches available for purchase, with special cases (such as the iPhone Mini) being made under exclusive contracts. The best lead they have so far is to try to use displays designed for the front part of a foldable phone, but they’re yet to strike an agreement.
TIL that display manufacturers are also part of the reason why we aren’t getting small phones and why it’s probably even harder for manufacturers like Fairphone to make them.
If you really want expandable storage for media you can buy teeny tiny usb sticks that you can plug in when you want to use them. Not perfect but a viable alternative.
Personally I stream everything and I back everything up to the cloud, but more options are always good and I’m 100% for additional storage options.