If Apple produced an Iphone SE with battery life that lasted, by making it a little thicker, then people would buy it IMO. The problem with the small phones is they arecreated on the premise that they should be crappy phones.
Of course everyone has a different version of what they consider crappy but bad battery life has got to be at the top of most people's crap-o-meter
iPhone 13 Mini was as you say. In every way as good as the full size iPhone but small. I hear it was quite an engineering challenge. I love the thing. The people of earth did not buy it.
It was a self-fulfilling prophecy to launch the iPhone mini during Covid, offer it 2 years, and say no one wants them. Especially when the SE proved people have no aversion to a normal sized phone meant for human hands.
Of course everyone has a different version of what they consider crappy but bad battery life has got to be at the top of most people's crap-o-meter