We looked into adding Google Sheets workflow nodes in the past, but for any operation other than reading from a public spreadsheet, the user must provide a token obtained through Google’s OAuth 2.0 authorization flow, which is something we can’t replicate within the workflow engine as it requires user action.
You could use the server-to-server authentication method outlined here but it’s quite a bit involved, and it requires you having a G Suite account and doing a lot of setup on the Google side.
You could then take the token generated through this process and use the HTTP Node to make requests against the Google Sheets API.
If that’s not an option, you can also use Losant’s data tables feature to store additional data within your application. Tables are subject to some pretty strict limits in a sandbox environment, so you would have to move your application to a paid organization plan to do anything production-ready within them.
Let us know if you pursue the Google Sheets option and if it’s a smooth process! We’d love to hear if it’s something our users can easily accomplish.