Darin B. There are multiple ways to do this.
You can go to Mixpanel integrations, and there you'll see a connector that allows you to bring Bigquery data to Mixpanel.
Or you can use Mixpanel API to get this done.
Make sure that your data is in the format that Mixpanel will accept, else it'll all be a mess.
I can help with this if you need. Lemme know.