Need help figuring out how to embed credentials.json for googlesheet to work hidden from my repo

The app works fine when the cred.json for the goolesheet API used to collect submission from a form, using the app. However, i want to be able to embed the json file secretly without it being esposed on git. All attempts and trials for using secret.toml isn’t functioning.
Is there a clear path to embeding a cred.json file while making my app work file and my cred not exposed