Where should I work on the integrations?

I’m testing the feasibility of using an interactive avatar for a client application. This client has an app where users need to make multiple daily entries for tracking purposes. I’ve tested the interactivity as just a shell of the application, and it worked great. Now, I need to understand how I’ll handle integration with the user’s Google Calendar or Google Sheets. Should I set up these integrations with Google on the Heygen platform or through GPT?