Additionally, in windows (linux too?) one could use Moonlight / Sunshine to compute on the GPU and stream to secondary device (either directly, like say to a Chromecast, or via the iGPU to their monitor). Latency is quite small in most circumstances, and allows for some interesting tricks (eg: sever GPUs allow you to split GPU into two “mini-gpus” - essentially, with the right card, you could host two entirely different, concurrent instances of GTA V on one machine, via one GPU).

A bit hacky, but it works.

Source: I bought a Tesla P4 for $100 and stuck it in a 1L case.

GPU goes brrr