I was specifically talking about Vulkan. You can use the GPU through higher level APIs like OpenGL or D3D11 just fine and those are supported on more hardware than Vulkan.

Only collectively so, when you have both GL and D3D11 backends.

OpenGL is not portable.

Technically it works on Windows, but that’s only true if you’re happy with 11 years old version of the standard, OpenGL 3.0: https://github.com/Const-me/GL3Windows#building-and-running GPUs have changed dramatically over these 11 years, i.e. that version is way too old.

Technically, OpenGL doesn’t work on majority of ARM devices. They use OpenGL ES, not quite the same thing.

Vulkan works on most of these, with the only exception of Windows devices who have Intel GPUs older than Skylake, i.e. older than 2015.

There are a ton of GPUs out there that don't support Vulkan but shouldn't have any trouble running an image editor. By using Vulkan when it doesn't provide much of a benefit for your use-case, you're just artificially limiting your audience.

This project is using wgpu-rs, which already exposes a API that's a bit easier to work with than Vulkan.

wgpu-rs has backends for Vulkan, Metal, DX12, DX11, and GL (partial). The primary backends are the lower-level graphics APIs that are in active development: Vulkan, Metal, and DX12.