The author has been weirdly reluctant to support new OS features, but I've been using Day-O[1] for years, it has a customizable time format[2] that could easily do 8601 [1]…
The author has been weirdly reluctant to support new OS features, but I've been using Day-O[1] for years, it has a customizable time format[2] that could easily do 8601 [1]…