I can confirm Proton functionality in full for the base unmodified game now.
I've been playing the game for over a day, doing various types of content as well as using TP. No crashes, no issues whatsoever, aside from what I mentioned before where loading up mods like Radial Mount or VKBasalt will cause the game to freeze.
OS: Garuda Linux
Kernel: 5.18.13-zen1-1-zen
CPU: Ryzen 2700X
GPU: Radeon 6900 XT
Memory: 32GB
DE: Plasma 5.25.3 (Wayland)
All I did to get to this point was set up a non-steam game in Steam, point it to the GW2.exe in the data folder, and tell it to use Proton GE 7.26. It worked right out of the box once I deleted gw2radial from the addons folder.
I've gotten some additional performance out of the game by mimicking several of the commands from user_run to the launch options in Steam. This is what I'm running right now:
MESA_GLSL_CACHE_DISABLE=0 MESA_DISK_CACHE_SINGLE_FILE=1 mesa_glthread=true RADV_PERFTEST=aco DXVK_HUD=fps,gpuload DXVK_ASYNK=1 STAGING_SHARED_MEMORY=1 WINEFSYNC=1 %command%