Short answer: most likely not achievable 100%. Long answer: possible if the right conditions are met.

If someone tells you differently and provides a simple answer they most likely don’t fully understand the problem.

There are only 2 ways to restrict traffic you either use a firewall or a proxy. firewalls work at the TCP/IP layer and proxies at http layer. Let’s focus on IP layer because these apps likely use HTTPS and SSL pinning making it impossible to proxy their requests without modifiyimg the app and the TV.

To block it at the IP layer you need to know Netflix and Google IP addresses. Their services are highly dynamic and change IP addresses all the time.

Google provides a list of IP addresses. Netflix I’m not sure. Read this page until the end: https://support.google.com/work/android/answer/10513641?hl=en

You would need to scrape this information and update your firewall rules frequently to avoid it breaking. And this would not prevent access to other Google services.

I think this is all very impractical and you are likely to give up during the process. A more reasonable setup is to do something that gets you closer to the final goal but has some flaws.

You could block DNS resolution to all domains and only allow certain domains. This way only play store and Netflix domains could be accessed. This can be achieved by having a configurable DNS server like pihole https://pi-hole.net/.

This won’t prevent your TV from accessing other services but it will tell your TV that they don’t exist or that they are located in the wrong IP address and your TV will fail to connect.

But this is not perfect. If your TV has some hardcoded IP addresses or it uses a different protocol to resolve the domains it needs it will still be able to connect to external services.

If your safety was on the line this method would likely not be viable but because your likely trying to protect from some general chinese corporation data gathering practices or preventing someone in your house to use the TV for other means this should be enough.