Updated 8Bitdo firmware lets you use official Switch SNES controller. Sorry if this is old news, I only just realised that this is possible. What a joy to use my SNES with
Amazon.com: Kinyanco 2-Pack Replacement SNES Controller Super Controllers, Game Controller Gamepad for SNES Original Super Entertainment System : Video Games
SNES Controller for SNES Super Nintendo System - Walmart.com
NINTENDO SWITCH - Online Super Nintendo SNES Controller - BRAND NEW | eBay
Super GamePad Wireless Controller for SNES Classic Edition® – My Arcade®
Nintendo 64 controller - Hardware - Nintendo Official Site
SNES Controller : ID 131 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Super Nintendo Entertainment System Controller - Hardware - Nintendo Official Site