Ah, custom date and time formats? It might be possible, at least for Gregorian calendar - might not hold true on all calendars.
Even then, I'm a bit hesitant to add new features at this time:
I'm moving away from date/time format specifiers in general at this time as it is prone to errors if not done well and is not really user friendly (one can argue custom date/time format might make things better for users).
My job with the Clock add-on at this time is to modernize and update existing features. This is more so as Clock add-on is not my own add-on.
Most importantly, I'm limited in what I can do now (will explain in the next post).
