Now that wefwef is integrated for the mobile version of the website, is it possible to have a setting to make it the default view for the desktop too?

Why not just bookmark m.lemmy.world if that's how you want to browse? I'm not seeing what a server-side setting buys you?

You should ask the developers of the old.reddddit.com redirect addon to migrate their code. That was one of my favorite browser addons back in the day when i used reddit.