It sounds like you downloaded the wrong (copycat) app; Google Home IS
free. Make sure it says the app is published by "Google LLC". If you
have an Android device, you want this:
https://play.google.com/store/apps/details?id=com.google.android.apps.ch...
Unfortunately, what you want to do is called Screen Mirroring because
the apps you want to cast are not cast-enabled. But, Apple declined to
support that feature on their devices. That is why you can mirror on
your Android device but not on your Appl...
While I would love to see one with more storage, Google will not comment
here on their plans for devices. They wait to announce them publicly at
one of their events.
You are not talking to Google here. We are users volunteering to help
other users. We can't make changes to Chromecast. Please use the
Feedback option link that I gave you to suggest features to Google.