I own 2 copies of the game (1 via Steam and 1 via the standalone Launcher).
I installed the Steam version and until now, used the “-provider Portal” Steam Launch option to switch between them. With Lunar new Year approaching I decided that, typing 2 words to change Versions, is too much of a hassle and looked for an easier solution.
Turns out, it’s really simple: By adding the GW2.exe, from the Steam installation, as a “Non-Steam Game” you are able to create differnt Shortcuts, with differnt Launch options, for the same Game.
Wanted to play GW2 on my Linux Laptop (Steam Proton is easier than setting up the original Launcher), also thought about buying a Steamdeck in the future. No, you cant lauch the 2 different Versions at the same time and based on a quick Google Search, most Multilaunch Tools (GW2Buddy, GW Multi-Launch, GW Launcher) dont seem to support Steam Login.