HIGHLY unlikely ... but if the pop singer and Super Bowl champ ever welcomed the cameras to document their every move, it would become the "biggest reality show ever" -- so says ex-NFLer and "Baller Wives" star Channing Crowder, who tells TMZ Sports the entire planet would tune in!!

"Taylor Swift is worldwide," the former Dolphins star said. "Most reality shows are national. This would play in Australia, this would play in the damn North Pole and everywhere you wanna say -- India, Egypt. Like, it would be the biggest reality show in the history of reality shows."

Of course, celebrity couples have been known to let the cameras detail every part of their lives in the past ... from Jessica Simpson and Nick Lachey to Britney Spears and Kevin Federline and more.

Crowder knows what it's like to open his doors for the country to see -- he appeared alongside his wife, Aja, on the VH1 series in 2017.

The Chiefs superstar is no stranger to reality TV either -- people aren't going to let him forget his dating competition, "Catching Kelce" -- but Swift is famous for trying to keep most of her private life out of the spotlight ... so don't hold your breath, folks.

There's no doubt it would be a hit, though ... as fans have been watching their every move after Swift was spotted at Kelce's games the past two weeks.

Speaking of football -- we also talked to Crowder about his gig with "Inside the NFL," which airs Tuesday nights on the CW ... and he said the whole team is amazing.