In the Rust graphics community, we have My First Renderer about four times, and no good renderers. It's about a year of work to get to where you can load the standard glTF examples and render them. Those are all small static scenes. Then you hit the scaling, performance, and dynamic update issues, where it gets hard.

The effort level for a good renderer in Rust is not yet known, but it's above two developer years. I'd guess three to five. Currently, there are three failed efforts and one in progress with some EU funding.

For multi-platform (desktop, laptop, browser, phone) add another year or two. All those use Vulkan, but with slightly different subsets and constraints.

I'm a user of renderers, not a developer of one.