Unfortunately, no, not really. All the apps that allow you to watch NFL games (Fox Sports Go, NFL, ESPN, CBS, NBC Sports) all require a cable/satellite subscription to use them. While CBS is a stand alone subscription. But always remember, you can still watch most of the games with an OTA antenna.
As for Sunday Ticket, there are restrictions on who can subscribe to the streaming only package. You must be a student or you must live in a building that does not allow installation of satellite dishes.
Playstation Vue offers NFL Redzone to their Core subscribers and above. Last year I just watched local NFL games via OTA antenna. This year though, I plan to subscribe to NFL Redzone and see how that plays out.
You can watch live NFL games on an ATV4 in the US, but not for anywhere near free - nor is it particularly easy to set up the first time. You'll need a foreign NFL GamePass subscription and a SmartDNS service subscription for starters.