[sudosysgen]

Small focal length cameras only have an advantage when the sensor size is the same. If you are decreasing the sensor size and keeping the resolution constant, the "small focal length" camera has zero advantage. There is no difference between a 4mm lens at f/2 that is a, say, 30mm FF equivalent and a 30mm full-frame lens at f/15. Precisely zero difference.

[defaultname]

If my grandma had wheels she'd be a bicycle.

[sudosysgen]

The two cameras produce exactly the same image. I guess your grandma really is a bicycle.

It's exactly the same reason why 50mm f/2 lens produces the same image on a full frame camera as a 75mm f/2.8 lens on an APS-C 1.5x camera. It's just that instead of multiplying by 1.5 you're multiplying by 8.4.

Indeed an iPhone 13's ultrawide will provide exactly the same image and bokeh as a 13mm f/15.1 lens on FF