БП 2.4.1

import pandas as pd

sessions = pd.read_csv('sessions.csv')
sessions['session_start'] = pd.to_datetime(sessions['session_start'])


def get_profiles(sessions):

    profiles = (
        sessions.sort_values(by=['user_id', 'session_start'])
        .groupby('user_id')
        .agg(
            {
                'session_start': 'first',
                'channel': 'first',
                'device': 'first',# допишите код
                'region': 'first'
                #'user_id': 'nunique'# допишите код
            }
        )
        .rename(columns={'session_start': 'first_ts'})
        .reset_index()
    )

    profiles['dt'] = profiles['first_ts'].dt.date
    profiles['month'] = profiles['first_ts'].astype('datetime64[M]')

    return profiles


profiles = get_profiles(sessions)

print(
    profiles.groupby('device'),
    profiles.groupby('region') # допишите код
)