Then you can skip all the CI/CD stuff (it's overkill for something like this) and just send a plain fetch from your app's backend (NOT the frontend/client!! Don't expose your Github tokens to your users!). You can either use their JS SDK or just send the raw HTTP commands.
I wrote an ansible pipeline that pushes config backups, json and ndjson, to a GitHub repo. It just uses the “git” cli tool to clone the repo, commit any changes, and push those commits to “origin/main”.
Only piece that you have to be a bit careful with the guarding credentials or token you will be using for the “git” commands. In my case we use Hashicorp Vault for secrets management so I can just checkout the token to use from there.