I did a simple test and oauth2-proxy 452 seems to be a interesting option!
It’s a simple oauth proxy, therefore I could protect my streamlit application behind a google-login page.
Please be aware that oauth is not a trivial flow so, consider wisely all your requirements (i.e. logout, security, etc) 
Simple demo:
demo - streamlit + oauth_proxy 09-06-2020 15-55876×428 2.16 MB