https://www.polygon.com/2017/9/29/16387374/snes-classic-controllers-nes-compatible

There were way more people who wanted an NES Classic than were able to get their hands on one. So far, Nintendo seems to have done a better job of meeting the demand for the SNES Classic (although we’ll see how that holds up over time). Either way, the overlap in the Venn diagram covering NES Classic owners and SNES Classic owners doesn’t represent a massive number of people so far.

Having said that, those lucky few will have plenty of controllers to go around. (While the NES Classic came with one gamepad, the SNES Classic includes two.)