An FCC filing has been found that confirms a SNES-style controller is on the way to Nintendo Switch. The filing, spotted by ResetEra user Link83 only shows the rear of the controller. It does feature the HAC model number, which is what Nintendo use to signify Nintendo Switch hardware and accessories.
When Nintendo Switch Online first introduced NES games, they released NES-styled Joy Cons for members. Perhaps we will see something similar with the SNES-styled controller, or it could well be a Nintendo Switch Pro Controller.
Nothing official has been confirmed yet but with the next Nintendo Direct probably airing next month (there’s usually one in September). It seems like the perfect place to finally announce SNES games coming to Nintendo Switch Online.