I have followed the steps you described in your [How To]. Everything seems to be working now, except changing the resolution of the video card.
I had optimus-manager and optimus-manager-plasma installed. I removed them and defaulted to envycontrol. Now, the output of glxinfo | grep renderer is
GLX_MESA_copy_sub_buffer, GLX_MESA_gl_interop, GLX_MESA_query_renderer,
GLX_MESA_copy_sub_buffer, GLX_MESA_gl_interop, GLX_MESA_query_renderer,
Extended renderer info (GLX_MESA_query_renderer):
OpenGL renderer string: Mesa Intel(R) Graphics (RPL-P)
I have tried both “hybrid” (currently selected) and “integrated” in the Optimus GPU Switcher, but the results are the same, i.e., no way to change the resolution of the video card.
I am considering reinstalling Manjaro, but I would rather not do that and find a solution…