Modern fighting games aren’t really designed for 6 buttons. I guess if you want to play SF6 with only face buttons that could be neat, but you’d still want to map parry and DI to shoulder buttons. The reality is that developers know that most pad players have 4 face + 4 shoulder buttons and most stick and leverless boxes have 8 buttons.

That said, 6 face button pads definitely exist. Most of the ones I’ve seen are from Hori, but there are quite a few brands that offer one.