Non-hacky Thunderbolt 3 eGPUs like the Razer Core do offer a loopback mode where the video feeds back to the laptops screen over the TB3 cable. The extra traff

Non-hacky Thunderbolt 3 eGPUs like the Razer Core do offer a loopback mode where the video feeds back to the laptops screen over the TB3 cable. The extra traffic on the wire does incur a small performance penalty over an external monitor though.