Ability to shift Capture Time in half-hour increments instead of just whole hours

I just returned from India recently where I took several pictures (hundreds) with both my iPhone and my Nikon Z7.  Upon return, I realized that I had forgotten to change the time zone on my Nikon.  

Now I am stuck with hundreds of pictures where I can't shift the Metadata Capture Time to Indian Standard Time (which is 5h 30min ahead of GMT)!  Has no one before me faced this problem all these years?

Am I missing something?  Is there any easy way to shift Capture Times in half hour increments (instead of whole hours)?

With the population of India being what it is, I would categorize this as a bug rather than an app improvement request.  Please help.