gsettings didn’t work in my case. Which is why i guess it’s libadwaita. Btw, i’m on XFCE.
edit: though, toggling light/dark via gsettings might work.
editedit: it didn’t. But GTK_THEME=<theme> did. Which is kinda troublesome still, since you can’t switch session variable content for the current session. Needs a wrapper script now.