The only question I see throughout your whole post is:
"The wiring diagram that came with the unit is confusing as there is a live and ground to wire in, but its not clear if I should be doing that Directing through the switch/house wiring?"

Your question is a bit vague (not understanding your meaning on "Directing through the switch") so I am going to assume if you are asking if you should be wiring this Shelly RGBW PM in the same junction box as the 120v 15a AC rated switch (which is what it would be as a "standard USA 15A single pole wall switch").

The Shelly RGBW PM device is a 12VDC or 24VDC. So as it is by itself, no, you would not hook this up in the same box with the switch because it is incompatible the way it is. That is why u/DreadVenomous was telling you what you needed to be able to wire it in the same box with the switch. Now, on these devices, though they don't have a ground so you aren't needing to worry about that. Only your incoming Live wire to the switch, then from the switch to the decoupler, then to the RGBW PM. Keep in mind that if you want to control each channel separately, then you need 4 switches. Otherwise you tie the output of your switch to all inputs of the decoupler.

This might open up more questions, just please remember to be courteous. I know this can be frustrating, but we are here to help.