In reply to @maxeaubrey:matrix.org
Doesn't work in games with 64-bit builds either (e.g. Celeste, Poly Bridge), and there's nothing obvious as to why (I mean, it technically "works" in that it occasionally shows heavily corrupted blocks over where UI elements would be, but that's the extent of it for native stuff)

I see, I did enable that and now I have a new error:

[user@nixos:~/nixos]$ /bin/sh\0-c\0/home/user/.local/share/Steam/ubuntu12_32/reaper SteamLaunch AppId=1390190 -- /home/user/.local/share/Steam/ubuntu12_32/steam-launch-wrapper -- '/home/user/.local/share/Steam/steamapps/common/SteamLinuxRuntime_soldier'/_v2-entry-point --verb=waitforexitandrun -- '/home/user/.local/share/Steam/steamapps/common/SteamLinuxRuntime'/scout-on-soldier-entry-point-v2 --  '/home/user/.local/share/Steam/steamapps/common/APICO/run.sh'\0
chdir "/home/user/.local/share/Steam/steamapps/common/APICO"
ERROR: ld.so: object '/home/user/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/user/.local/share/Steam/ubuntu12_64/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS64): ignored.
ERROR: ld.so: object '/home/user/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/user/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/user/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
pressure-vessel-wrap[59774]: W: "/run/current-system/sw/bin/getent" is unlikely to appear in "/run/host"
pressure-vessel-wrap[59774]: W: Found more than one possible libdrm data directory from provider
/nix/store/6jccsbgsxjvyydl25x2hx6hrfmyqd0wf-dconf-0.40.0-lib/lib/gio/modules/libdconfsettings.so: undefined symbol: g_assertion_message_cmpint
Failed to load module: /nix/store/6jccsbgsxjvyydl25x2hx6hrfmyqd0wf-dconf-0.40.0-lib/lib/gio/modules/libdconfsettings.so
/nix/store/75sqkz9mdqfzv1q9dcrkvzk73p630nxr-glib-networking-2.78.0/lib/gio/modules/libgiognomeproxy.so: undefined symbol: g_task_get_source_tag
Failed to load module: /nix/store/75sqkz9mdqfzv1q9dcrkvzk73p630nxr-glib-networking-2.78.0/lib/gio/modules/libgiognomeproxy.so
/nix/store/75sqkz9mdqfzv1q9dcrkvzk73p630nxr-glib-networking-2.78.0/lib/gio/modules/libgiognutls.so: undefined symbol: g_source_set_static_name
Failed to load module: /nix/store/75sqkz9mdqfzv1q9dcrkvzk73p630nxr-glib-networking-2.78.0/lib/gio/modules/libgiognutls.so
/nix/store/75sqkz9mdqfzv1q9dcrkvzk73p630nxr-glib-networking-2.78.0/lib/gio/modules/libgiolibproxy.so: undefined symbol: g_task_get_source_tag
Failed to load module: /nix/store/75sqkz9mdqfzv1q9dcrkvzk73p630nxr-glib-networking-2.78.0/lib/gio/modules/libgiolibproxy.so
/nix/store/p2lfk2avsrbjvz080sw9nz4ancl7sx0f-gvfs-1.52.2/lib/gvfs/libgvfscommon.so: undefined symbol: g_task_set_source_tag
Failed to load module: /nix/store/p2lfk2avsrbjvz080sw9nz4ancl7sx0f-gvfs-1.52.2/lib/gio/modules/libgvfsdbus.so
/nix/store/p2lfk2avsrbjvz080sw9nz4ancl7sx0f-gvfs-1.52.2/lib/gvfs/libgvfscommon.so: undefined symbol: g_task_set_source_tag
Failed to load module: /nix/store/p2lfk2avsrbjvz080sw9nz4ancl7sx0f-gvfs-1.52.2/lib/gio/modules/libgioremote-volume-monitor.so
bwrap: Can't bind mount /oldroot/etc/group on /newroot/etc/group: Unable to mount source on destination: No such file or directory
Uploaded AppInterfaceStats to Steam