I'm trying to do a time series model without a datetime field in python. Is this possible?
You can use timedelta function from datetime to achieve this, starting from a known date.
Example code can be something like,
from datetime import datetime, timedelta

start = datetime.strptime('2021-01-01', '%Y-%m-%d')

all_dates = [start + timedelta(x) for x in range(10)]

print(all_dates)

Replace the range(10) above with the sequence of the actual days in your dataset.