Sadly, "PWA mode" (it probably should be called "Install to desktop") was being worked on under "Site Specific Browser (SSB)" name, but due to lacking resources

Sadly, "PWA mode" (it probably should be called "Install to desktop") was being worked on under "Site Specific Browser (SSB)" name, but due to lacking resources work will be scrapped. More info here: https://bugzilla.mozilla.org/show_bug.cgi?id=1407202 https://bugzilla.mozilla.org/show_bug.cgi?id=1407202