The Date content type can be interpreted as a Number, which yields a Unix time value. However, the reverse does not work. A Unix time value interpreted as a Date does not yield a valid Date, even though the UI is happy to let you specify that interpretation. Nor can a Date be initialized with a Unix time as the “Specified Date”.
Many web service APIs use Unix time values and it seems awfully cumbersome to make those into Date content types. Currently the best I’ve found is to create a Date initialized with the string “January 1, 1970 00:00:00 UTC”, followed by an Adjust Date, adding the desired Unix time value as seconds. Ugh.
Is there something I’m missing? I’m workflow/Shortcuts novice.