This is super cool and almost makes it possible building PWAs that only need a dumb http server to deliver the app as a bunch of static files and still allow users to synchronize data between their devices. It still depends on the tracker but if the user could change the tracker it sounds like it's currently the best way to get clients to communicate with each other without depending on a server provided by the PWA.
Does it actually work though? Ironically my experience is that windows api + proton are a more stable target than anything linux native. Even valve doesn't get it always right when shipping linux versions of their own games. See https://steamcommunity.com/sharedfiles/filedetails/?id=30358... for example.
It varies by game. https://areweanticheatyet.com/ is an interesting resource for that because they also track announcements by developers about whether or not linux support is eventually planned.