I tried it with a less typical case (the Warsaw, Poland transit app).

I'm impressed that it worked at all and got quite far. Though it is still broken in many ways (random geo locations), the menu bar on top...

The problem is that many web apps are quite simple, while native apps get trickier when it comes to UX. The LLM doesn't work well if it has to interpret animations or cross-correlate map data with locations on a map.