Nice. This one seems to actually work! (at least on beta)

It does not work, I'm on Linux (Manjaro KDE Plasma) and the steam button on my steam controller still opens Big Picture Mode. I hate it because it's gotten so much stutter and lags often it's unusable now.

holy ♥♥♥♥, this worked, thanks!

This doesn't work. God I hate this nonsense piece of software so much.

♥♥♥♥♥♥♥♥♥ this was so helpful, I recently upgraded my pc and this was a problem I didn't had before, thank you so much for this

Отлично! Не все герои носят трико и плащи.

@RyhanZFX
OK. With just Steam running and focused, check if Guide opens Big Picture mode or not.

sorry for the messy languange, i dont speak english as my first languange, basically ive done more testing, i can definitively say that even just adding say a PCSX2.exe as non steam games with the correct parameter to launch a game, disable steam overlay in the menu settings, do your advise and add the action sets and other more tweaks, it still opens the overlay for me, glossi for some reason actually has it disabled correctly in the app setting (theres option there disabling the overlay for glossi), but steam still bugged out by attempting to open a non existant overlay

i do remember now, it used to work correctly prior to Steam updating the whole UI and settings back in 2023 and replacing the big picture to the one from steam deck

yeah for me it still triggered the overlay no matter what, i can try your method thank you. the only reason im doing this is because how easy it is to connect Playnites with its versatile features like playtime hours to Steam with my non steam games with the glossi integration, im happy with how it works but for disabling it for certain games i just couldnt find a more proper way, it just bugs out that invisible overlay with overlay sound that disables input until i press the guide button again. Actually its not even a glossi problem it just how it refuse to completely disable the guide button for controller and its finnicky to set it up for certain games

@RyhanZFX
Although I focused the instructions/title on Guide opening BPM, the process blocks Steam actions that are triggered by a Guide-only button press.

So if instead of Guide = 'open overlay' you'd be happy with a chord e.g. Guide + B button = 'open overlay', then try the instructions above but also map the open overlay keyboard shortcut to a button somewhere on the Guide Button Chord Layout. (When I tested it out I found it best to also close the overlay with the chord.)

Or did you already try the main instructions but still find Guide triggering the overlay?