How do I use customize timezone for celery crontab?

I'm currently integrating python celery to do some task. What I really want to acheive is to assign crontab with CUSTOMIZE TIMEZONE.

For example:

task_timezone = datetime.now(timezone('US/Eastern')) + timedelta(hours=7)

Each task is designed to run on US/Eastern time plus 7 hours as timezone.

Already tried Celery beat - different time zone per task

Not working on my end. What I did in my code as follow:

Method 1:

nowfun = lambda: datetime.now(timezone('US/Eastern')) + timedelta(hours=7)
....
'schedule': crontab(minute='1', hour='1', day_of_week=[1, 2, 3, 4, 5], nowfun=nowfun)

But this code gives me this error:

Can't pickle <function <lambda> at 0x7f74326264c0>: attribute lookup <lambda>

So I tried method 2:

def nowfun():
    return datetime.now(timezone('US/Eastern')) + timedelta(hours=7)
....
'schedule': crontab(minute='1', hour='1', day_of_week=[1, 2, 3, 4, 5], nowfun=nowfun)

But this time, I got this error:

tzinfo argument must be None or of a tzinfo subclass, not type 'function'

Any idea how to resolve this issue?