If I zoom and pan in the Render Window, is there a way to set the view to the actual resolution, like a hotkey or button?

Try SPACE-G with your mouse inside the window that you want to “GO” to home.

Space-G only seems to centre the view, not expand it to its full resolution.

think you can expand view only with Ctrl+B and to the full-screen not to the render's view resolution

That's useful, too. In Arnold (Maya) you can zoom to true resolution with a hotkey.

True resolution is critical, but is one of the many missing basic features of the new renderer as far as I know

Am I missing something? I just hit ‘g’ or ‘h’ to home the render view and it resets the zoom to 1-to-1 and centers the image.

I think we may be talking about different things
With Mantra we have the “Render View” which does indeed have 1:1 or “true resolution” homing.
With Solaris and Hydra delegates the closest thing we have right now seems to be the “Image viewport” which does not have this.

@alexsomma: How do you get true resolution in Mantra Render View? I can only zoom manually to make the image closer to real resolution. The G key just centres the scene.

alexsomma
I think we may be talking about different things
With Mantra we have the “Render View” which does indeed have 1:1 or “true resolution” homing.
With Solaris and Hydra delegates the closest thing we have right now seems to be the “Image viewport” which does not have this.

I think the OP was referring the to Render View pane, not the hydra view.

litote
@alexsomma: How do you get true resolution in Mantra Render View? I can only zoom manually to make the image closer to real resolution. The G key just centres the scene.

If you are indeed using the Render View pane, then the G or H keys reset the zoom and center the image. This functionality is missing in the Scene View pane for Hydra(solaris) in the Image View mode.