Note that depending on your setup (please provide more info when asking for help) your audio might not be limited. In some cases you can set your volume way above 100%.
Additionally in some applications you need to set the hz frequency that the program is running in Proton search for: PULSE_LATENCY_MSEC=30, 60 or 90
I recommend Kvaesitso, it is well integrated and the app switchers triggers properly. I have tested Lawnchair but it behaves like a separate app and not part of the system which Kvaesitso does really well.
gamescope Error vulkan: vkGetPhysicalDeviceFormatProperties2 returned zero modifiers for DRM format 0x38344241 (VkResult: 0)
gamescope Error vulkan: vkGetPhysicalDeviceFormatProperties2 returned zero modifiers for DRM format 0x38344258 (VkResult: 0)
Yet the final straw seems to be:
gamescope Warn xwm: D-Bus call to get unit corresponding to pid 2291408 failed!
sd_bus_call(g_dbus, message, UINT64_MAX, NULL, &reply)failed with ret -30
Gamescope WSI Creating Gamescope surface: xid: 0x2a0005e
gamescopereaper Info reaper: Parent of gamescopereaper was killed. Killing children.
gamescopereaper Info reaper: Parent of gamescopereaper was killed. Killing children.
Gamescope WSI Failed to get Wayland objects
(EE) failed to read Wayland events: Connection reset by peer
Game Recording - game stopped
gameid=2073850
Removing process 2291192 for gameID 2073850
It seems there are some Nvidia drivers and gamescope compatibility issues, so you will most probably need to match Nvidia drivers with gamescope versions.
I see you paste some logs but they have expired, did you run steam through the terminal and got them? If you do so, you'll get a log of steam trying to launch the game.
Some time has already passed, so try to uodate your system again, it will probably fix it.