That's basically the whole reason an entire instance popped up dedicated to the topic (db0) AND its main community is the 10th largest in the lemmyverse.
The main mods and a whole lot of people came here.
This is one of the success stories of a major sub migrating here.
We use the ISO-8601 date and time format, mostly. We separate the portions by points, not dashes, though. So a typical date looks like this: 2023.12.22. If we shorten it without the year, it's 12.22., or 5.12. We say it with just the numbers, without the points, and shorten "hónap" (month) to "hó". So its "5. hó 12", basically "5th mo' 12".
For time we use the 24H format, regularly even in everyday speech. If it's very clear that you are in the late afternoon or evening, you just say "6 o'clock 24" or "13 o'clock 46".
So always from bigger to smaller "powers". It's auto-sorted on most filesystems, table of contents etc. and very clear in everyday use. It's nice.
Hungary.