I've had pretty much zero issues with gw2 bar a bit of stuttering here and there in some maps by just adding the gw2 exe to steam as a non-steam app, installing Proton-GE-Custom (https://github.com/GloriousEggroll/proton-ge-custom) and using that for gw2's compatibility proton version, having gw2 run in dx11 mode, and using the following for launch options:
Still, would prefer to use the ArmoredVehicle package, but as of right now, this setup works fine, with relatively standard performance. Well, Gw2 is a bit sluggish to launch (the launcher takes its sweet time to load, and occasionally just refuses to launch at all). The latest Proton-GE-Custom fixed a crash related to ArcDPS with Gw2, as well.
Trading post works fine, bit low fps but not outside of my expectations even on Windows. Pretty much only issues I have are with the launcher. Slow and laggy, lazy to start up, spams journalctl with the following warning: "Window manager warning: Window 0x5000004 sets an MWM hint indicating it isn't resizable, but sets min size 1 x 1 and max size 2147483647 x 2147483647; this doesn't make much sense", seems to force itself to stay above all other windows, can't drag it very far around the desktop (seems to act much, much larger than it really is, and refuses to go beyond the edges of the monitor at all). Once ingame, no issues.