Google can expose podcasts to users through many different mechanisms, including:
- Google Search results as a link to a podcast page or as an embedded episode player
- Google Search App for Android (requires v6.5 or higher of the Google Search App)
- Google Podcasts app
- Google Home
- Content Action for the Google Assistant
- Android Auto
Google simply needs to find and index your podcast in order to make it available. See here to learn how to make your podcast available on Google.