You could use Node.js or Python code steps to make a conditional statement to branch your logic out, then you could either make the API calls directly to Google Sheets or call another workflow to actually perform the work.
Branching within a workflow is a highly requested feature, it’s on our roadmap. But for the time being you’ll have to use conditionals in code steps to handle this particular problem.
That will teach you the basics of using Node.js code steps in Pipedream workflows. This will show you the basics of using data from other steps, and exporting data from Node.js code steps.
Then you’ll be able to use if statements to conditionally export the data format for Google Sheets based on the topic of the webhook payload.