Not the one you have been asking, but you can eigher install Lutris, and then install GW2 from there, or download it on Steam. Those are 2 fairly straightforward ways. If you have an ArenaNet account (rather than an account binded to Steam), but still want to use Steam as your launcher - just write “-provider Portal” in launch options.
Epic also gave money to Lutris, while Epic’s CEO was smearing Linux users on twitter, so I wouldn’t count on Epic’s stance on things and where some of Epic’s money going aligning any time soon. Those megagrants feel very disingenuous to me (doesn’t mean that those money do not help those “underdog” projects, though).