First ensure that your appointments are exporting to your Google calendar in Upvio.
Then follow the below instructions from Google:
Embed a calendar on your website
- On a computer, open Google Calendar. You can only get the code to embed in your website from a computer, not the Google Calendar app.
- In the top right, click Settings.
- On the left side of the screen, click the name of the calendar you want to embed.
- In the "Integrate calendar" section, copy the iframe code displayed.
- Under the embed code, click Customize.
- Choose your options, then copy the HTML code displayed.
Your embedded calendar will only be visible to people you've shared it with. To allow all visitors to see your calendar, you'll need to make it public.