What is Metal

The requirements are preliminary, and that MacOS has not been publicly released. It may be a mistake to invest money now for requirements that could change before its official release.

On macOS, Metal supports Intel HD and Iris Graphics from the HD 4000 series or newer, AMD GCN-based GPUs, and Nvidia Kepler-based GPUs or newer.

AMD links:

GCN is fabricated in 28 nm and 14 nm graphics chips, available on selected models in the

Radeon HD 7000,

HD 8000,

200,

300,

400and

500 series

of AMD Radeon graphics cards. GCN is also used in the graphics portion of

AMD Accelerated Processing Units (APU), such as in the PlayStation 4 and Xbox One APUs.

NVIDIA links:

Kepler was Nvidia's first microarchitecture to focus on energy efficiency. Most

GeForce 600 series,

most GeForce 700 series, and

some GeForce 800M series GPUs were based on Kepler, all manufactured in 28 nm. Kepler also found use in the

GK20A,

the GPU component of the Tegra K1SoC, as well as in the

Quadro Kxxx series, the

Quadro NVS 510, and

Nvidia Tesla computing modules.

Kepler was followed by the Maxwellmicroarchitecture and used alongside Maxwell in the

GeForce 700 series and

GeForce 800M series.

from:

https://en.wikipedia.org/wiki/Metal_(API)

and links therein to other wikipedia pages

Metal is a low-level, low-overhead hardware-accelerated3D graphic and compute shaderapplication programming interface (API) developed by Apple Inc., and which debuted in iOS 8. Metal combines functions similar to OpenGL and OpenCL under one API. It is intended to bring to iOS, macOS, and tvOS apps some of the performance benefits of similar APIs on other platforms, such as Vulkan (which debuted in mid-February 2016) and Direct3D 12.

from:

https://en.wikipedia.org/wiki/Metal_(API)

.

There is no way to add ThunderBolt to computer that left the factory without that capability built-in.

There is no hard information yet available about what cards will be supported.