There's the obvious: get an Amazon Prime account.
The local broadcast version: games on ESPN (and apparently, on Prime as well) are simulcast on a local broadcast station, accessible via antenna. BUT we know how well that worked out for some people this week for MNF
The added bonus for TNF being on Amazon? Amazon makes the TNF games available for free on TWITCH https://www.twitch.tv/nfl . For those of you without a Prime account and problems tracking down a local broadcast, this might be the freebie option for you.
Figured I'd share early, but will likely bump this a few weeks from now when the game gets closer