To be fair, that's the low power Ally with a pretty significant 20% off sale.

I'm not well educated on the power difference, but a quick google search shows the cheaper Ally gets about 60% the benchmarked performance of the more expensive Ally when plugged in. There's also a significant drop when not plugged in, but less severe (only about a 20% drop in fps). Source

I suppose the real question is how does it compare to a Steam Deck at that price, and if the drop in power is worth the price difference.