What aspected of iOS have you seen that do not work in a Mini? I have a 12 Mini and have not run into that problem. I’m not bothered by one-handed operation or not. I just don’t like the bulky and heavier phones and how they don’t fit well in pockets. I’m not going to switch to cargo pants just to accommodate my phone 😊.Most of this is caused by Apple making the more recent iOS versions seemed geared to needing larger and larger screens. They still haven't produced any iPhone designs that are some form of foldable design that would be durable. So you don't have the same product available that caters to someone that needs almost a tablet for a iPhone, or as a smaller design when you don't need to use the various apps over instead using it for cellular calls/texting mostly.
If they were to only update the Mini every couple of years I’d be fine with that.