I just came across this link and this seems like a neat idea but I am sure it will be harder in practice than the article makes it sound.
I wonder if you will have to specify the model of your car and they will send you mounting brackets made just for your car to make it fit. Many car radios are “universal fit” and come with the appropriate brackets, harness adapters, etc. that you specify upon their purchase.
Either way, this sounds like a neat idea and would be nice if they could make it work for not a ton of money.