If you want to try it, I have had success using fb_boot_drv instead of fb_drv in qemu. This was as a prelude to actually getting it to work on my hardware. In this case your resolution will be set based on whatever GRUB decides to set as the resolution, as I understand it. This can be quite large if the correct options are passed to qemu and you use the right firmware (I use the TianoCore firmware). IIRC I had to edit the driver manager or some such in order to prevent it choosing fb_drv (i.e. the VESA one). But that was in an older Sculpt. The newest one seems to have a preference of Intel -> GRUB -> VESA, so it might be using the GRUB one already? (As an aside, it doesn't actually check if the Intel driver fails, so if you, like me, have an Intel graphics adapter that it doesn't like, it won't fall back to the GRUB one, it'll just leave the screen blank).

Good luck,

Colin