Mods can delete this if they wish but it's not illegal and there's nothing in NFL's T&C's that prohibit it. So there is no reason to.
1. Buy an NFL Gamepass subscription in a none US country. India generally seems to be cheapest but you can shop around. It's all the exact same website but the NFL fudge the price depending on popularity I assume. It's around $140.
2. Buy a good VPN service or a router with good built in VPN. Route all your traffic through Mexico. If a game is live in Mexico it will be blacked out on Gamepass and you can change your country to elsewhere. (Probably do this first before you buy Gamepass to make sure you get it working)
3. Watch all games live, on replay, get coaches film etc
Now I know some people are thinking this sounds shady, it isn't. The NFL don't care as they are making money. The only reason they can't sell to you in US is they already sold those rights to CBS etc. The only people that might care are the TV networks but again your not breaking any laws.