On the other hand, making the storage of datetimes based on UTC a best
practice, without tzinfo attached and assumed therefore, might make
integration easier.

On another other hand, setting tzinfo seems to have no real downside in
working with datetime types and I wonder why utcnow doesn't set tzinfo
while its at it.

At any rate, agreeing to have Dulcinea work with UTC at minimum and call
local.format_date* would be an excellent step.