Starting GW2 overlays on Steam with Proton. Set as Steam launch option for GW2. Change -provider Steam to -provider Portal if you use a Anet account. Change the 60 seconds of sleep to something lower if your computer is fast (you want to be in game before Buritto or Blish start).

a.sh

# Burrito overlay, put burrito_link.exe and burrito.x86_64 in the game folder.
echo -e "@echo off\nstart burrito_link.exe\nstart Gw2-64.exe -provider Steam\nexit" > gw2.bat; echo -e "DXVK_ASYNC=1 MANGOHUD=1 $(echo %command% | sed "s/Guild Wars 2\/Gw2-64\.exe.*$/\"Guild Wars 2\"\/gw2.bat/") &\nsleep 60\nchmod u+x burrito.x86_64\n./burrito.x86_64" > gw2.sh; sh gw2.sh

# Blish HUD, put the Blish.HUD folder in the game directory.
BHDIR=$(realpath "$(find -iname "Blish.HUD*")"); rm -f BlishHUD; ln -s "$BHDIR" BlishHUD; rm -f BlishHUD/BlishHUD.exe; ln -s "$BHDIR/Blish HUD.exe" BlishHUD/BlishHUD.exe; echo -e "@echo off\nstart Gw2-64.exe -provider Steam -autologin\nping -n 60 127.0.0.1>nul\ncd BlishHUD\nstart BlishHUD.exe\nexit" > gw2.bat; DXVK_ASYNC=1 MANGOHUD=1 eval $(echo %command% | sed "s/Guild Wars 2\/Gw2-64\.exe.*$/\"Guild Wars 2\"\/gw2.bat/")

I'm still getting Burrito as a black screen, and BlishHUD not at all. I posted a comment on the forum post I saw this linked to, but I am still having issues getting things to run right. Any insights would be nice.