The Exact Opposite is true.
For the past two years, the NFL has actually had a Heritage Program where they encourage players and coaches to wear flags on their helmets (players) and jackets/shirts (coaches).
You can look it up. Below is one article I found from last October that mentions Puka Nacua's participation.
NFL celebrates international diversity with NFL Heritage Program
Published: Oct 19, 2023 at 10:27 AM
The National Football League will celebrate players' and coaching staffs' cultural origins this season with its NFL Heritage Program, with all 32 teams represented.
Across Weeks 7 and 8 of the 2023 season, over 330 players and coaches will return to the field wearing international flag decals -- with players adding flags to their helmets and coaches wearing patches on jackets -- to represent the ever-growing pool of various nationalities and cultures that make up the League.
Fans will see 70+ nations and territories represented by athletes including
Tua Tagovailoa,
Fred Warner,
Amon-Ra St. Brown,
Puka Nacua,
Chris Olave,
DJ Moore,
Jimmy Garoppolo,
Aaron Jones,
Efe Obada and
Jordan Mailata, among others, as well as coaching staff across 17 clubs including Bill Belichick, Arthur Smith, Ron Rivera, Brian Daboll and more.
"As we continue to prioritize the NFL's growth globally, we're proud to have our players and coaches honor their backgrounds through the
NFL Heritage Program," said Peter O'Reilly, executive vice president club business, international and events at the NFL. "This initiative allows us to celebrate the heritage, families and cultures that make up the fabric of the League, and truly showcases the growing global reach and impact of the sport of football and the NFL."
Participants can choose to wear the flag of an international country or territory where relatives have been born or where they've lived for over two years. Players will wear these flag decals alongside the American flag, and are able to represent their backgrounds throughout the remainder of the season.
"My grandmother was born and raised in Samoa, and recently left us in 2021," said Nacua, Los Angeles Rams wide receiver, who will display the Samoan flag on his helmet. "To be able to represent our family's heritage and feel like she is here with me on the field is the most incredible thing. I'm proud to play for all of our Samoan fans out there and can hopefully inspire future generations of Samoan athletes."