In the past year, there have been several requests to have Nudge support local time zones instead of UTC:

• Feature request: Support the local timezone
• UTC vs Local Time
• Feature request: use system local time instead of time for a specific time zone (e.g., Z / GMT)

Turns out, as Kevin M. Cox explains in Nudge deadlines in local timezones, the functionality has been there all along, just previously not well documented or used.

I tested this out myself, and it really is just a matter of changing <date> to <string>.

With a string deadline in my .mobileconfig profile, I still had a one-day grace period (I’m in Pacific time in the U.S.):

      <key>requiredInstallationDate</key>
      <string>2023-03-27T00:00:00Z</string>
      <key>requiredMinimumOSVersion</key>
      <string>13.2.1</string>

With a date deadline in my .mobileconfig profile, the deadline had already passed:

      <key>requiredInstallationDate</key>
      <date>2023-03-27T00:00:00Z</date>
      <key>requiredMinimumOSVersion</key>
      <string>13.2.1</string>