VRcover released their fake leather replacement thing for the index
https://vrcover.com/product/valve-index-interface-foam-replacement-basic-set/
I kind of liked their rift version, and this one looks a lot more plush. However, $40 is literally the same price as getting 2 official replacement gaskets for the index
https://store.steampowered.com/app/1072820/Face_Gasket_for_Valve_Index_Headset__2_Pack/
So for pure hotswappability, it doesn't seem worth it.

My biggest sweat problem is foam the back of the index. They should have made that velcro so you could take it off and wash it.