Here we are assuming that Santa's magic does not allow for time travel or changing the hours of darkness across half of the earth. If Santa only travels at night on late Christmas Eve or early Christmas Day according to the local time zone of where he is at any time, how many hours does he have to deliver presents around the globe?

Assuming you just want darkness any time between noon Christmas Eve and noon Christmas Day, he would have 45 hours as there are sections of Alaska and Siberia north of the Arctic Circle which are dark all day these days which are covered by the -9 and +12 time zone. So he gets 21 hours from the time zones on top of the 24 hours of darkness.

The +13/+14 and -10 to -12 time zones do not help him as none of those areas are as far north, so the nothernmost regions are dark far earlier and remain dark far longer.

https://en.wikipedia.org/wiki/Time_zone

According to this article, it is about 34 and a half hours.
I don't think it quite takes into account that the terminator itself (the line dividing the dark part of the earth from the light) won't be in total darkness because of refraction of sunlight through the atmosphere. I think that would reduce the hours down to about 32 hours.
https://factcheckni.org/articles/special-christmas-investigation/?utm_source=copilot.com

The International Date Line hasn't been mentioned... You'd lose the day going crossing east meaning that you'd miss Christmas altogether and gain or repeat a day crossing west so you could have Christmas twice... It would therefore be advantageous to travel in a westerly direction.

The International Date Line is also known as the "Line of Demarcation" because it separates two calendar dates. When you cross the date line traveling east, you subtract a day, and if you cross the line traveling west, you add a day.

https://www.timeanddate.com/time/dateline.html