First, welcome to the Streamlit Community!
I checked in with our team and they know that we are a bit light on examples for this! They are actually making up an app example for just this application of secrets (connecting to BigQuery) and that will be ready soon.
Edit: sorry forgot to add this in, we are still working on making the Docs live but for now check out this link for details: Notion – The all-in-one workspace for your notes, tasks, wikis, and databases.
As soon as they pass that on I will link it here for you!