Using different Vulkan ICD loaders on Steam Flatpak

I’m using the flatpak version of Steam because, on the runtime/native version, CS:GO wouldn’t start (inserting -nojoy in the launch options didn’t work).
Is there a way to use other ICD loaders in Steam Flatpak? It only sees RADV and i would like to use AMDVLK because I’ve read that Doom Eternal runs better with AMDVLK.

Not a huge issue tho, RADV is just fine.