I'm trying to install 2 smart wifi switches to replace 2 dumb switches in a box. 1 switch powers a dining room light. The other switch powers two kitchen lights that turn on/off together. As expected, I found 3 wire bundles entering the box (with 2 wires in each sheath, one black and one white). One of the black wires is hot (connected to a red nut). 2 of the black wires are loads going to the lights. All of these wires are on the same circuit because they are run through the same breaker.
This all makes sense to me. However, I expected the 3 white (presumably neutral) wires to be connected in a bundle. I would then tap that bundle for the smart switches, but they are individually capped. They also have a small amount of voltage in them when I tested them with a voltmeter. But all the lights and switches work with the dumb switches, so there doesn't seem to be a problem.
My question is: should I bundle the 3 white wires together? Was that just an oversight when they were being installed? And then can I tap that bundle for smart switches? How can I be sure the 3 white wires are the right neutrals?
Here is the smart switch I would like to install. I don't have the manual yet because I don't want to buy it until I'm sure it will work.
I confirmed that this box is not grounded and does not have a ground wire.
And updating with pictures of two of the three lights. The third is hard to disassemble, but its wiring runs with one of the two pictured. These all look standard to me. Black with black, white with white, and grounded to the box. All lights work. Note that although the wiring in the box look new, these wires likely were originally installed many decades ago. The house was built in the 1920s but has been updated over time, so the wiring could be quite old.