FWIW, neither of these relate to Tinderbox prototypes but to the attribute value tables used in Displayed Attributes and Get Info.
The Date Picker is a macOS feature so unless it has a hidden option, the request would imply building a custom date picker to replace the OS one.
Currently, the same tables display Date type attributes using the user’s macOS locale short date setting plus the hh:mm of the attributes time (i.e. omitting the seconds part). Thus, on my UK locale t(on 8 aug 22) a date/time of now, displays as “0/6/08/2022, 11:34”. Note the locale dependence. In this US for instance, the day and month would be reversed and the year might show only the last two digits. When the attribute value is being edited, the $DisplayedAttributesDateFormat is used so I see “6 Aug 2022 at 11:34:12”. This default longer format makes sense as we are global community but different countries use different ordering of month and date so ‘6/8/22’ is ambiguous: 6th August or 8th June? In what century (it matters for historians), etc…
So if you are seeing seconds in un-selected data attribute, change you macOS settings. If you see seconds when editing a Date change $DisplayedAttributesDateFormat.