I understand that Apple did not make enough money to make it worth their while to continue the iphone mini line. However, it does seem like there is a profitable business for someone there given how beloved it was/is.
I only traded out my iphone 12 mini just recently for an iphone 16 pro (likely the last apple product I will ever buy but thats another story) and aside from the camera it is basically the same. Just heavier, awkward to hold and slightly worse designed.
No major player wants a smaller screen because it has downstream impacts on the pipeline of addictive material and ad pixels they can stuff into ocular nerves.
There are lots of phone manufacturers who have no ads business. They just make phones so why would they care?
Size is dictated by trouser pocket size/handbag size and usage. Editing photos and movies to upload onto social media is probably better on a big screen.
Also screen size is dictated by common panel sizes, as low volume will mean a higher price.
Folding screens and iPad Mini's existence suggests people want larger screen real estate.
There are still bound to the screen resolution dictated by the platforms/environment. A maker selling an android phone with a 480x640px screen would face a huge uphill battle to see any sales.
Going for a smaller physical screen means higher DPI, so higher production costs and quality control issues. It can make more sense to buy cheaper, low DPI screen and make the whole device bigger to match the needed pixel count.