Have you seen -> https://gitea.wildfiregames.com/0ad/0ad/wiki/GettingStartedReinforcementLearning

The Vulkan renderer is on by default, for the shaders, you can either compile them yourself (which is a bit annoying) or you can use the script to download the current built ones https://gitea.wildfiregames.com/0ad/0ad/src/branch/main/source/tools/spirv/get-nightly-shaders.sh (on Linux)

Another question: how can we compile and use the Vulkan renderer on the main branch of gitea?

You could use this for import: I think you might have to modify the meshes though, because the game meshes are often just "flat planes" and they need some thickness for printing. Also keep in mind that a lot of the details is stored in a normal map. I think there is a way to turn the normal map into geometry via nodes editor. 

Don't use cargo but install the distribution package instead.