3% of sales means a sub-par experience for those users. Every app developer will say “oh yeah let’s test on the pro and normal sizes. Mini might break but that’s ok.”
I have an old original SE, that I used to use for low-end testing, but it tops out at iOS15.
Currently, my Mini13 is my low-end test, but I’ll probably need to get a new phone, sooner or later (“later” works for me).