GloriousEggroll has released a new custom pre-release build of their Proton fork based on the latest  Proton release with support for DOOM Eternal.

This is my build of Proton with the most recent release of vanilla wine, has ffmpeg enabled for faudio by default, and all of Proton's patches ported over to be applied to wine, as well as wine-staging and vkd3d.

All patches:

-Warframe screenshot F6 patch -FFXIV Launcher patch -Mech Warrior online patch
-Assetto Corsa HUD patch -Vulkan child window patch
-sword art online gnutls patch
-d9vk integration
-vkd3d integration
-protonfixes integration
-FAudio with FFMpeg enabled (fixes audio/voices in multiple games)
-All of Valve's wine proton patches. Yes. All of them.
-wine staging patches
-various wine hot fixes for wine functionality that fix regressions per version

Change log:

-Updated wine + staging to 5.4-git/upstream for DOOM Eternal
-Added ValveSoftware/wine#85 VK_KHR_get_surface_capabilities2 and fake support for VK_EXT_full_screen_exclusive for DOOM Eternal
-Added ValveSoftware/wine#83 which fixes some crashes in DARK SOULS III (374320), Nier: Automata (524220), Sekiro: Shadows Die Twice (814380)
-Added some missing registry entries that prevented Batman: Arkham Knight from starting on a clean prefix
-Cleaned up/removed unused mf_install verb in protonfixes in preparation for newer mfplat alpha patches (coming soon)
-Removed '-wolcen lords of mayhem 'blob head' fix' as the game devs fixed it internally per update 1.0.10.0
-Removed 'plasma systray fix' as it didn't really benefit anything, and actually interfered with some games.
-Removed Detroit:Become Human patch as it's already been upstreamed
-Cleaned up some duplicate patches and updated our current patches to work with latest wine-git+staging/git
-Updated vkd3d
-Updated dxvk
-Updated FAudio

Note: DOOM Eternal currently requires vulcan-loader/vulkan-icd-loader 1.2.135 and for AMD also requires mesa-git. ACO did not work for me with DOOM Eternal when I tried it, but llvm worked fine.

Download Proton 5.4-GE-2 from GitHub