On Thu, Nov 2, 2017 at 3:31 AM, Daniel Ford <dfnojunk@gmail.com> wrote:
"Then you can use any zoneinfo-aware 'localtime()' implementation to convert the absolute time to the local civil time."

I've not yet found an Arduino library with such a function.  They all seem to operate from text data.  But I'll keep looking.

The library discussed in this list includes source code for one.
 
There are many scenarios where one would want to know the exact time and not be near a PC or smartphone.

One may not be near another clock either.  But, I'm not here to debate the market for your device ... I'm just trying to describe ways you might use the TZ database as it exists.
 
That would also require that their 'computer' be on 24/7, assuming the user wants to know the accurate time at any time of the day or night.

I don't think I implied such a requirement.  Occasional synchronization should be sufficient, like existing radio clocks.