What're your plans regarding OpenGL support? Is that something you care about or not at all?
The current state being that wgpu supports it, and as such we can already use it in bevy by setting the wgpu back-end env variable, but in bevy it only works for 2D stuff (trying the 3D examples of bevy lead to a Naga error because, IIRC the PBR stuff uses features that cannot work in OpenGL or something like that).
(If you tell me that OpenGL is something you want to support and it's just an oversight, I can file an issue on github with much more details, and would even be willing to contribute)