Ack, it seems that you are right. Indeed, glGetString(GL_VENDOR), glGetString(GL_RENDERER), and
cout << glGetString(GL_VERSION) return
Intel
Mesa Intel(R) UHD Graphics 630 (CFL GT2)
4.6 (Compatibility Profile) Mesa 22.0.1
which suggests that glutInit (&argc, argv) set up an OpenGL context on the Intel GPU, not the NVIDIA GPU.
I’ll continue poking around but does anyone have a quick fix for this?