How to connect google sheet to Power BI

"Secured enough" is obviously subjective and depends on your scenario.

Google do have an oAuth2 API which apparently provides secure access to protected Google Sheets. The challenges will be:

1) getting Power BI to work with Google's oAuth2 API - this might be possible but at the least it will be quite difficult.  There are no obvious doco or blog posts to follow.

2) getting Power BI to read the result - it doesnt appear (from my quick scan of Google's oAuth2 API doco) that it provides the same easy method to return an Excel file as the result.

I'd be really happy to be proved wrong, if someone has the time and persistence.  Right now I have neither :-)

Another way is to make use of PowerBI python script feature. (Note : Better Privacy, IMHO)

1. Set up python script to connect to Google Sheets (https://towardsdatascience.com/accessing-google-spreadsheet-data-using-python-90a5bc214fd2) (Note: You need to enable Both Google Drive and Google Sheet)
2. Use that python script in PowerBI as connector. ( https://docs.microsoft.com/en-us/power-bi/desktop-python-scripts ) (Need a bit modification such as pandas) Note: Make sure you install required python library such as "pip install pandas" etc

Below is sample of my script

import gspread
from oauth2client.service_account import ServiceAccountCredentials
import pandas as pd
from pandas.io.json import json_normalize

scope = ['https://spreadsheets.google.com/feeds','https://www.googleapis.com/auth/drive']
creds = ServiceAccountCredentials.from_json_keyfile_name('C:\\Users\\USER\\Downloads\\YourServiceAccountJSONFile.json', scope)
client = gspread.authorize(creds)
sheet = client.open('GoogleSheetFileName').sheet1
data= sheet.get_all_records()

df = json_normalize(data)
print(df)