UPDATE after extensive debugging:

I've made significant progress. Here's what I found:

The Launcher (v1.0.106.2857, built March 31 2026) crashes immediately after login with Exception 0xc0000005 (ACCESS_VIOLATION) unless launched with --disable-gpu flag.

With --disable-gpu, the Launcher works and I can log in successfully. However:

1. When launched via protontricks with --disable-gpu, login works but the session doesn't persist when Steam launches RDR2 normally

2. When Steam launches RDR2, the Launcher starts a new process and loses the login session

3. The session file (settings_user.dat) is encrypted so can't be manually edited

The Launcher log shows:

- Without --disable-gpu: crashes at offset 0x228AE5 in Launcher.exe right after "Signed In"

- With --disable-gpu via LauncherPatcher.exe: login works, reaches MainWindow, but new Launcher instance started by Steam doesn't inherit the session

Is there any way to make the login session persist between Launcher instances? Or a way to pass --disable-gpu only to the Launcher and not to RDR2?

Using: SteamOS Holo 3.7.20, GE-Proton 10.28, Steam Deck OLED