We'd love to re-use your DateFieldtype, wrapped by a Vue component to deal with Unix timestamps. For that, we would need to be able to set the localization of the displayed date to German: Instead of "March 6, 2009" we'd need "6. M盲rz 2009" or at least "06.03.2009" (which should be easier to enable for you, since we'd only have to pass a format string while keeping US localization).
To render the same string in the index, a way to format the timestamp to a German date would also be needed in PHP. :)
I have a new date fieldtype in the works on feature/v-calendar that has a _lot_ more flexibility around date formats and masking. I'm quite sure we can work this out.
New Date fieldtype is now on master. It respects the locale setting in config/app.php so you get this right out of the box:

That sounds awesome, I'll be testing it tomorrow! Thanks a lot!
Uhmm... Are we supposed to use DateFieldtype and TimeFieldtype separately now? If so, why does DateFieldtype still emit updates as .format('YYYY-MM-DD HH:mm')? 馃檭
Ah my mistake. Reopening and bringing the time field back inside 馃槀 Got a little over zealous.
There we go. Fixed in defdfb8e.
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New Date fieldtype is now on
master. It respects thelocalesetting inconfig/app.phpso you get this right out of the box: