1.4.10 Reflow and mobile user agents

As I am trying to edit the Understanding text of 1.4.10 Reflow, I am wondering whether to lack of mobile user agents that offer reflow (apart from the Dolphin browser on Android, maybe some others) means that WCAG 2.1 as a whole can only ever be met for a desktop-oriented accessibility baseline?
If authors want to claim conformance to WCAG 2.1 also on mobile devices, is there a need for a particular exception or a particular statement saying that

- 1.4.10 does not apply to mobile UA; or
- can in principle be met on mobile OSs, as evidenced by the Dolphin browser for Android, so this.is a UA issue;
- 1.4.10 is implicitly met by other broadly equivalent means, e.g. the double tap gesture to zoom-in to selected columns (this means you can selectively zoom in and out of content without having to scroll)
- something else?

Not sure how to handle this…
Detlev