I notice a previous similar request:
Converter to change gregorian date to jalali on view layer of discourse
But more promising is this one:
Error in loading dashboard reports when using moment-jalaali.js
which links back to this earlier one
How to properly display jalali dates for Persian language
(edit: oops I see this was linked earlier)
I would recommend a change to the title of this topic, perhaps:
How to display all dates and times in Jalali (not Gregorian)
(I think what’s needed is purely in display - the actual timestamps in the database will not be changed. These timestamps will be seconds-since-1970)