Rendering a region in solid viewport shading? Is it possible to render a region where it is rendered by cycles, but everything outside the render region is in solid viewport shading?

Use case is if I have multiple objects lined up one by one and I want to work on their materials. I would like to be able to see the objects in the viewport, but render region doesn't allow that in rendered viewport shading.

I am not asking how to render a region (CTRL+B). I already know how to do that.*
It looks like it's a bug, or missing feature, from what I could gather from this bug report: https://developer.blender.org/T63064