I’m going to be moving to Lausanne in the next couple of months and I’m considering importing my 2017 Mercedes Benz GLC 300 Coupe. From what I've read on some of the other threads here I’m beginning to think that it might not be worth it. It is not the import costs that I’m worried since it will be part of my ‘personal belongings’ rather it is what I might have to do in order to make it drivable in Switzerland e.g. engine emissions standards, lights, it has aftermarket Apple Carplay and a stealth hitch etc. Is there an easy way to determine upfront the potential costs and hassles or should I just plan on selling the car and buying another one when I get to Switzerland?

Don't bother importing that, especially with the aftermarket modifications. Just buy a car once you get here.

Call the Lausanne and Geneva Mercedes Dealerships and see if they have experience getting a US spec car certified which is the same model as yours.

I can't imagine that retrofitting CarPlay or a towbar would cause any issues?

Then you need more imagination

Just because a towbar is legal in the US does not mean you can have it on your car in CH. If its an official Mercedes part you might be lucky... if its aftermarket is there a high chance it isnt approved.

There's no need to speculate. Some models are homologated for tow bars, other don't, and this list is public. Just check the model in any towbar shop, for example https://www.kupplung.ch/