I've just sold my Quest 1 and upgraded to a Quest 3. I know that VO is now in AppLab at a rather expensive £20 but I also still have the APK that I extracted from the Oculus Go 4 years ago. Is there any difference between them, i.e. is it worth spending the £20? Nicer graphics maybe?

Well, unless something changed, originally the Oculus Go apks were __NOT__ compatible with the Oculus Quest 2 when the q2 came out. It was a pretty big deal at the time - at least, there was a lot of noise at the q2's launch iirc. A quick search brought this as first result.

As for what's different/changed/etc with the actual application, assuming you could even bypass that backwards compatibility issue, that's a question for Incarnate. My intuition would expect the newer edition on applab would have vastly improved integration with the system, let alone being properly designed for the Quest headset and therefore more visually appealing... but I dunno. Maybe even change how controllers work (Go was 3dof vs the 6dof of the quest series)

I'd also just say *support the devs for their hard work!* but i'm biased.