On the Nintendo website it says this about the snes controllers:
Super Nintendo Entertainment System Controllers are compatible with Nintendo Switch software titles that require only the directional buttons and A/B/X/Y/L/R Buttons, such as Super Nintendo Entertainment System – Nintendo Switch Online.
Which is different from what it says about the NES controllers:
Please note: Nintendo Entertainment System Controllers can only be used while detached from the Nintendo Switch system, and only to play NES – Nintendo Switch Online games
https://www.nintendo.com.au/
So that sounds promising.