Linux you can get for “free” with DXVK or VKD3D-proton. MacOS is an even more niche platform than Linux as far as gaming is concerned and is not a tough sell to skip considering the total lack of market share in games. iOS and Android generally come in a pair so unless you’re only targeting one you need to support multiple APIs anyway. Xbox requires Xbox specific APIs so you need explicit work there. Every other console uses a bespoke API that will require another backend in your engine (yes Switch technically supports Vulkan but that is not the recommended path from Nintendo, you will likely end up with an NVN backend).

D3D11 gives you both desktop platforms that matter for games, everything else will require multiple backends anyway so if you only care about desktop it’s a fair choice.

Contrary to urban myths, non-xbox consoles aren't that found of Khronos standards either.

Valve's efforts on playing Microsoft only games started ~10 years ago with Proton (which is more like an umbrella project for ~15 software components like Wine and DXVK). Today, proton is surprisingly good. Their bet paid off, and allowed them to make SteamDeck. Most if not all new games play fine out of the box, with 0 tinkering. Older games sometimes have issues.

Since DXVK exists and Apple dropped OpenGL, the latter gains you access to Android and that's about it, unless you're ok with ES 3.0 contexts and a lackluster set of extensions (ANGLE on Metal).

AFAIK the non-Xbox consoles either don't support OpenGL or we reportedly don't want to use their implementations.