Are your clients set to use the AppleTV as a gateway? That's a fundamental requirement to ensure the packets your devices send in reply get passed back to the tailscale network.
Yes, the clients I've attempted this with so far (iPhone running tailscale) I have configured to use the Apple TV as an exit node. When I do so, there is no internet connectivity. When I switch it to another exit node I have in my tailnet it works flawlessly.
