1) It's supported by cronie. I bet it's supported by many other crons.
2) "Great" news! The software in the Systemd Project only officially runs on Linux, so "it's not portable" is a really bad counterargument when "alternatives to some Systemd Project feature" is the discussion topic.
hmm, when did that get added? Last time I checked, the only timezone you could specify was UTC (which was one more than cron supported, but still insufficient.)