How can I set timestamp precision with SQLAlchemy and Postgresql

Question

I’m using flask-sqlalchemy with postgresql database.

I have some Columns with timestamps. I'm setting them like this:

class Return_attempt(db.Model):
    ''' Data related with each return attempt'''
    time_waiting_collection = \
        db.Column(db.DateTime(), server_default=db.func.localtimestamp())
    time_collected = db.Column(db.DateTime())

Example of timestamp stored in db (server_default): 2020-02-19 19:41:36.975644

Now, I want to use this timestamp in the frontend but I'm only interested in the time with precision to the seconds. In the example above, I want to display it like this: 2020-02-19 19:41:36.

So my question is, how can I store the timestamp with that precision? Or is there any way to easily manipulate the format of the displayed timestamp? (I'm using python and jinja2 for templating)

Thank you!