CheckMag | Resident Evil 6 would make a great battery sipping handheld experience, except it's unplayable

Looking for a decent triple A experience that wouldn't immediately flatten the battery on my ROG Ally X as I travel through a multitude of airports and long haul flights this summer, Resident Evil 6 seemed to fit the bill. I've never given it the time of day given the reviews at launch, but decided to take the plunge when it was recently for sale on Steam at $4.99.
Looking at RE6 from the battery life perspective was the right choice. At 1080p, the native resolution for the Ally (Available on Amazon) and Ally X, and maxed out settings, 10 watts would happily keep the game running between 40 and 80 frames per second. I could even lower the wattage down to 8 watts and still lock the frame rate at 30. Pretty reasonable when trying to maximise battery life. This would give me well over 3 hours of play time.
However, there is a bug that makes the game almost completely unplayable. The bug seems to have been around for a while, with users reporting the issue as early as 2015, and further reports cropping up over the last few years.
The bug constantly switches to keyboard and mouse, then back to controller, forcing the character to do something completely unpredictable such as aiming somewhere totally different, or turning around entirely. The most annoying thing is that this seems to occur most frequently when in the middle of a firefight, making aiming almost impossible. You can spend ages navigating corridors, and not have it switch at all, but as soon as the action gets frenetic, it happens multiple times every few seconds.
Forums suggest disabling any sort of Steam input, relying on the game's native controller input. However, this has no effect. The most common fix seems to be disabling Steam entirely when playing, which for Steam OS or Bazzite, is impossible. No gyro controls are active, and shaking the device when there isn't any action doesn't trigger the issue, similarly it's not accidental presses of the rear keys, as these bring up menus of their own and have no impact in other sections of the game.
After managing to play through Leon's campaign, struggling with the issue, I started on the Chris campaign which is action heavy, making certain sections almost impossible to complete.
As for the game itself, the save system is irritating if you have to stop play for a period of time, as you are often loose a good chunk of progress. The ammo collection system seems unbalanced, as playing through the Leon campaign saw almost too much of it, with the Chris campaign constantly giving me skill upgrades instead of ammo. Even with the upgraded skills that are supposed to give more. For such an action heavy section where you are expected to shoot everything, this seems counterintuitive. Quick time events are an unwelcome irritation, and the inventory management of the previous games is gone, much to its detriment. And what on earth is smashing people in the chest to revive them all about?
Perhaps this doesn't impact the Steam Deck, but running Bazzite, you’d expect it to be more or less the same. Nevertheless, I have been enjoying Resident Evil 6 for the most part, but the controller switching is the nail in the coffin.