Next to the laptop, believe it or not. https://support.apple.com/en-us/HT208544 https://support.apple.com/en-us/HT208544 eGPUs are supported by any Thunderbol

Next to the laptop, believe it or not. https://support.apple.com/en-us/HT208544 https://support.apple.com/en-us/HT208544 eGPUs are supported by any Thunderbolt 3-equipped Mac1 running macOS High Sierra 10.13.4 or later The key is to realise that modern cables coming out of laptops are basically extensions of the PCIe bus. The bandwidth through them is phenomenal. It's entirely feasible to run an external GPU. However, you don't really need one. I am a casual gamer who uses my laptop (got an Xbox too though), and even with the embedded GPU strategy/city building/etc type games work fine and look great. The Mac isn't a good platform if you're a capital-G "Gamer" but if you just want some entertainment on long flights and the like it works just fine. Go grab Steam and off you go. I don't think I'll be using Stadia any time soon as a consequence.