WCAG v2.1 for mobile website evaluation

Hi everyone,

I hope you can help me with a question I have been thinking about for a
while.

The updated WCAG v2.1 guidelines seem to be device independent but I was
wondering if all the non-compliant issues would be discovered if someone
was to conduct an assessment of a mobile version of a responsive site using
just an iPhone (and VoiceOver). Is this sufficient or should the desktop
version also be assessed (using a desktop screen reader like JAWS or NVDA).

Thank you very much for your help.

Cheers,
Matt