KDE and Microsoft Outlook allow you to add the ISO or American week number to the calendar.
Probably other software has this icon
Uhm? The site doesn't show what week it is..? It's currently week 9 of 2025, but the site shows W7 of Q1. (Maybe that's what you meant? Searching for the current week in the quarter?)
oh, I was being subtle since everyone was asking for a feature request.