I have a 13 mini and would advise that you and I abandon our lines of thinking/hope :p

They'll never make another phone this size, and accessory manufacturers ofc take their cue from Apple. I thought about some bespoke/custom keyboard for mine as I have experience with USB periphials but I kept coming back to "will I have this phone in 4 months?"

I've considered more than once stocking up on good condition used 13 minis, just in case mine breaks or apple stops replacing the batteries

Enjoying it for 4 months is 4 months of enjoyment :)

"Mitch, do you want an apple? No, eventually it will be a core!" - Mitch Hedberg

I'll join in and that will make it 8 months!