Essentially the title.
If only S2 (previous connection point from light switch to bulb) is truly required, then, wow, that makes things way easier to install.
I guess electrically it makes sense, I’m just weirded out it does not show in the instructions.
S1 and S2 are only for the activation switch. You connect the actual device that gets controlled to Line Out.
If your setup doesn’t require a physical switch, then nothing gets connected to S1 and S2