Gaming

To build on your excellent rundown I'd like to add that changing the OS isn't just a bother, it also removes the upsides of respective system. The deck is great for longer sessions of simple games, Valve has done wizardry with the power consumption on its low power mode. But it all goes out the window on Windows.

For ROG a massive draw is Game Pass which of course is a non starter on Linux. Couple that with how the Deck UI isn't really available to the Ally (yet, might change soon) what already isn't great on the Ally gets worse on Linux.

From my limited hands-on experience with both the main issue I have is how much clunkier they are than a Switch. If I had to buy one today I'd go with the Ally though, the extra power means it is actually usable docked making it a very portable LAN device but I'd really like like 30-50% more such that 1080p works for more titles. Then it gets really interesting to me as something that can be used as the kids computer. Because the oldest has issues with the Switch not really having the juice needed for many Minecraft mods and wants to move into PC, but most switch time today is when we're in transit and away. And we're not going to lug a gaming PC around. A laptop would work but they're a lot more expensive and bulkier such that they can't be used in the backseat. So the Ally is pretty optimal, just slightly lacking juice the juice to drive a 1080p screen well in some games.