Give it a title, a date and a time. The time matters on the last day: once the target is today, days stop being a useful unit and the gadget switches to hours and minutes.
Choose working days and the count skips the days you do not work. Which days those are is a setting, because a working week is not Monday to Friday everywhere; a Sunday to Thursday week is a checkbox, not a workaround.
Both numbers are always available. A two week freeze is ten working days and fourteen calendar days, and the gadget will tell you either.
It refreshes itself. Nobody has to stand in front of the screen pressing reload, and the number does not quietly go stale overnight.
The count runs in the time zone of the browser reading it, and the gadget says so on its face so that nobody has to guess whose midnight is meant.