Others may have a longer answer to your question, but certainly it is possible to get an NVIDIA GPU for a desktop PC with a PCI bus. You can even get something that will work with your Mac or Windows laptop, you just need to buy a caddy to put the card in, for instance the Razer Core. Getting this working with a Mac is a bit more complicated than with Windows, you can find instructions online.
The GTX 1060 is adequate to get started with image processing, computer vision and deep learning because it has good single precision performance. For simulation, solvers, and other problems where high accuracy double precision is essential, you may need to look at a more expensive card in the Quadro or Tesla range. There is also the Titan V.
