Historically, when we've built Google Cal links manually, we've done this by adding the "?ctz=" querystring parameter into the Google Calendar URL.
So for Eastern Time, we've done this in the past: ?ctz=America/New_York (based on the values found here)
How the Google Cal output on hapily events goes now:
What would be ideal to inject time zone like this:
When adding "time zone" to Google Calendar events, this is what I'm referring to (where it says "(GMT-0:4:00) Eastern Time - New York")