But is there really much of a correlation? I know that's the conventional wisdom, but over-focusing on big markets is not a guarantee of ratings success.
For the past 20 years, NBC grossly overemphasized big cities like New York, Philadelphia, Pittsburgh and Washington in its NHL coverage (and similarly when it carried arena football). Viewership consistently declined throughout. Having teams in Chicago didn't help the WFL, the old USFL nor the original XFL, where both leagues' Chicago teams were participants in the worst-attended and least-watched games.
But the Alliance/AAF did well in the ratings as a largely regional southern league in relatively small markets—better than the USFL did this year.
Remember, this is—at its best—second tier football. Football is at its best when it connects with a fanbase. The 2020 XFL chose markets that, though they had NFL teams, also had enough openings in the February-to-April season to slide into the scene and engage fans. Seattle had no NHL or NBA team, and they embraced the Dragons. St. Louis of course went wild for the Battlehawks. You go back to 10 years ago, the most successful teams in the UFL were places like Omaha and Sacramento—mid-sized cities, smaller than the NFL, but enough attention to draw 20,000 fans a game most nights.
And when fans are engaged with a team, that does, believe it or not, translate into a national following that is good for TV, especially in this age where we are more connected than ever and people can move across the country while still keeping hometown connections. Take a look at what Buffalo has managed to do in the NFL; the Bills Mafia has followers nationwide. (Much of the team that helped build that, even in the darkness of those awful drought years, is now with the XFL.) Or the Green Bay Packers, for that matter. Then look at the Giants and Jets, and how irrelevant they are.
Big cities can be helpful, but they're not the be-all and end-all. A league built in smaller markets, especially when it has no pretenses of being the next NFL, I firmly believe such a league can be a success.