Writer here! I regret to inform you it does not. The original Z1 Extreme Ally, which is on paper considerably more powerful than the Deck, can only achieve meaningfully higher FPS when plugged into wall- on battery Z1 Extreme and Deck perform very close, as shown in the benchmark shared at the end of this one.
Since the Z1 Ally is even weaker than that, well...you get the idea. It performs significantly worse than Deck in real-world gaming scenarios, especially in handheld. The main thing we see from these benches is that the newer RDNA 3 architecture is more efficient in some ways even while cut down to this extent, but unfortunately the Z1 Ally is too cut-down to meaningfully compete with Deck in raw FPS unless your performance needs are lower— and you really want Asus' PCIe x8 eGPU connector.