The apps you get
Apple’s tech specs page for HomeView lists all of the apps it comes with, along with four additional Apple apps that are “available from iPhone.”
Apple
Although not explicitly stated, it appears that all four apps available on your iPhone work through your CarPlay interface. (The giveaway is audiobooks, which are books on all other devices.) All of those apps now have support for CarPlay, primarily for audio experiences. For example, you can’t read e-books with Books or news articles with News, but you can listen to audiobooks or news summaries.
CarPlay on your desktop
What happens if you use Spotify for music or podcasts? Or cloudy? Or Audible for audiobooks? What if you want to watch a YouTube or Netflix video?
Apple has a solution for this and it’s pretty clever. Existing audio and video apps that support CarPlay will automatically be available in HomeView, without the developer having to do anything at all. If a developer doesn’t want their app to appear in Apple’s Smart Hub, they can opt out using the Disadvantaged Locations feature, but otherwise all music, podcast, audiobook, and video apps that support CarPlay will work in HomeView streaming from your iPhone just as they would if you were in a car.
Apple
Apple’s CarPlay developer site has now been updated to mention how CarPlay audio and video apps work with HomeView.
This is a great idea. The simplified CarPlay interface used by the apps is more appropriate for this type of device, which is intended for simple consumption and not for editing your next big playlist. And developers can support both cars and HomeView at the same time in apps they already publish to the App Store. If they already support CarPlay, they don’t even have to update their app.