Accessibility testing an App

Hi everyone,

I emailed a few months ago for advice on how best to check the
accessibility of a website on mobile and desktop. Your feedback was very
helpful - so thanks again for that.

We have now progressed on, and I would very much like to check the
accessibility of an Android and iOS app (ideally against WCAG v2.1). Can
anyone talk me through how this can be done as it is difficult to see the
code behind the App. Is it enough to run assistive tech on it (i.e.
VoiceOver, Talkback etc). or is there a way to look at the code as well?

Cheers for your help,
Matt