

Kind of. You could only open the menus IIRC when you were not in a game, can’t recall the exact key bind though. At least, this was the case when I tried replicating the gaming mode session on my PC (I haven’t actually used a keyboard on my deck either). It was quite strange.
As far as I understand, the steps you linked to are currently the only way to do this. Personally, it’s not something I’d be willing to go through. That guide explicitly states that if you accidentally lose the keys, you’re not able to disable Secure Boot.
Additionally, since the SteamOS kernel needs to be signed manually, this seems like you could run into some “fun times” when SteamOS updates the kernel and loses the signature. You’d need to re-sign the image every time the kernel gets updated.
To me, the risks outweigh the rewards - especially since we don’t know how well BF6 runs on the deck. Of course, at the end of the day its a choice you have to make yourself, but that’s my take on the matter.