I find it highly annoying that these rather powerful handheld smartphone computers don't have decent port access for use with instrumentation, etc. A huge range of features comes to mind from Geiger counters, oscilloscopes, sound level measurement, light intensity, etc , etc. The potential to expand the smartphone capability is enormous yet no manufacturer has tackled it. Why not? Why aren't there multiple USB ports?…
Whoever I talk to those says "smartphones are damn too big", and yet no manufacturer produces reasonably-sized phones anymore, because it apparently "they wouldn't sell" / "market size too small". If this is too difficult, than your use case is orders of magnitude more difficult. Unfortunately everyone tries to sell to the same generic user, with very little actual space for differentiation targeting niches.
The smaller iPhones didn't sell well.