Using a Custom dll
Being able to use a custom dll on Steam Deck games (i.e. Reshade, Special K, etc).
Summary
If you want to use things like ReShade, Special K, Durante's DSFix, Great Ace Attorney fps unlocker, Trails in the Sky voice patches, et al. you'll need to add a custom dll to the game folder next to your exe. On Steam OS, that alone isn't sufficient though.
Authored by strudelkuchen, original publication
Instructions
Add the following to the launch parameters of the game you're dropping a custom dll into:
WINEDLLOVERRIDES="YOUR_DLL_NAME=n,b" %command%
Replace YOUR_DLL_NAME with whatever your dll is called, i.e. if it's dxgi.dll, replace YOUR_DLL_NAME with dxgi.
Example
Let's say you want to use reframework with Monster Hunter Rise: you would put the dinput8.dll file next to the game's exe and then change the launch parameter for the game like this: WINEDLLOVERRIDES="dinput8.dll=n,b" %command%
n stands for native and b stands for builtin, which means WINEDLLOVERRIDES="dinput8.dll=n,b" tells wine (proton): try to load dinput8.dll as native windows dll first and try the builtin version if the native load fails.
source: https://linux.die.net/man/1/wine (search for WINEDLLOVERRIDES)