Multiple problematic things in your log:
info: AMD Radeon RX 6700 XT:
info: Driver: 2.0.241
this means you're using amdvlk or the proprietary vulkan driver instead of mesa/radv, which is known to not work great with proton.
libGL error: MESA-LOADER: failed to open radeonsi: /usr/lib/pressure-vessel/overrides/lib/i386-linux-gnu/dri/radeonsi_dri.so: cannot open shared object file: No such file or directory (search paths /usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/dri:/usr/lib/pressure-vessel/overrides/lib/i386-linux-gnu/dri, suffix _dri)
probably broken (32bit) opengl driver install as well, which the game might need for it's launcher or something.
Hello @LightningRhino, we're using one issue per unofficially supported issue report, and usually I'd transfer this issue report to #6505, but in your case it's clear that you're seeing a NixOS specific Steam Linux Runtime - Soldier issue.
https://gist.github.com/LightningRhino/b19718a1d9659fdfa9afb6cf998767cd#file-gistfile1-txt-L1082-L1140 and https://gist.github.com/LightningRhino/b19718a1d9659fdfa9afb6cf998767cd#file-gistfile1-txt-L1248-L1324 tells us that mesa is outright broken in the container environment Proton runs inside.
Report this issue to nixpkgs for a NixOS package maintainer to ponder. https://github.com/NixOS/nixpkgs/issues/217344#issuecomment-1439198102 might be relevant.
ge-proton7-49x1 2023-02proton experimentalx1 2023-02PROTON_USE_WINED3D=1x1 2023-02PROTON_USE_WINED3D=1 %command%x1 2023-02
Compatibility Report
System Information
I confirm:
steam-699130.log
Symptoms
Game does not start at all with any tested Proton version.
Also GE-Proton7-49 does not work.
I always get a crash dump sending utility.
I even tested with PROTON_USE_WINED3D=1 %command%, which also brings the crash dump sending utility.
Reproduction
Start the game and wait for just 2-3 seconds.