I have never read or studied USB-C. However, it is pretty universal that one wire will carry power and another will be the ground. The other wires are for signals. In an old style A connector, there are 4 terminals (wires). However, the letters probably stand for something like "Universal Serial Bus". Which means that the signal is a serial cable, where one wire carries the information as a string of binary voltages as a function of time. In old "serial cables" there was a wire that carried the signal out and a second wire that provided an acknowledgment signal back. However, simply thinking this way is probably not sufficient as it does not explain an audio signal which is analog voltages. In some cables there are electronics built in to act as an intermediary. However, if you only had 1 to 2 splitter and no audio then I think you can be pretty sure that the wires are all just wire and no electronics inside.
As far as multiple charging is concerned, as long as your wall charger can put out lots of current then there should not be a problem with having a two devices receiving power. However, I suspect that if you were trying to provide the same signal to two devices without any intermediate electronics a more complicated device would be required.
There are bus systems where all of the devices are connected along a single cable. Here handshaking is required to tell which device to listen to the transmitter. Handshaking is basically like an address that is sent first and each device has a unique address. Think of this like the old party line phone system where there was only one wire. When someone wanted to call you they would ring a certain number of rings (your address) so that you would know the call was for you and you would pick up the receiver. The other folks who also had phones connected to this single line could hear the number of rings and so knew the call was not for them. So they did not pickup the receiver. Everyone shared one line and were suppose to be polite and not "listen in" to the conversations that were not for them! Wow! Days gone by when people were polite!
Why don't you just spend a little money and get a wall charger that has multiple outputs. Google the phrase "multi port usb wall charger"
As far as multiple charging is concerned, as long as your wall charger can put out lots of current then there should not be a problem with having a two devices receiving power. However, I suspect that if you were trying to provide the same signal to two devices without any intermediate electronics a more complicated device would be required.
There are bus systems where all of the devices are connected along a single cable. Here handshaking is required to tell which device to listen to the transmitter. Handshaking is basically like an address that is sent first and each device has a unique address. Think of this like the old party line phone system where there was only one wire. When someone wanted to call you they would ring a certain number of rings (your address) so that you would know the call was for you and you would pick up the receiver. The other folks who also had phones connected to this single line could hear the number of rings and so knew the call was not for them. So they did not pickup the receiver. Everyone shared one line and were suppose to be polite and not "listen in" to the conversations that were not for them! Wow! Days gone by when people were polite!
Why don't you just spend a little money and get a wall charger that has multiple outputs. Google the phrase "multi port usb wall charger"
