In a way, none of them are truly plug and play. The GMOS-01 needs to be connected to the headunits wires and adjust the speaker output for the chimes. As far as leaving the keys in the ignition I can't see how that is a possibility with someone, how can you leave your vehicle and not remember to grab the keys? lol. And with the lights, we have rundown protection so its irrelevant.
But yeah, I forgot about that little tidbit for plug and play. GMOS-01 is really handy to use. Only confusion I had when I set it up for my co-worker was when I saw both the accessory wires, I wanted to be 100% sure they both get joined together, not that I short anything out on it since it was for my co-workers wife.
edit: OP, I don't think it is an option without the onstar but I could be wrong, did your daughters truck come with steering wheel controls? If not then just the gmos-01 will be all you need. If she does, you will need another module to allow the steering wheel controls to work but it isn't truly needed if you don't mind sacrificing the feature.