On macOS, `cal -m 1` prints out January 2023. The man page reads "-m month Display the specified month." Googling for man pages gives other usages for the `-m` switch (like https://linux.die.net/man/1/cal) so it probably depends on system.

Depends. I have zsh running on Linux and Mac. On Linux, smorrebrod wins. And on Mac slowmovingtarget wins.