Indivision AGA is "almost" a graphics card as it gives a few more screen modes to the Amiga via HighGFX (OK, 1280x1024 @36Hz, which is impossible to show in anything but via Indy). Why almost? Because it uses the Amiga native graphics system and then SD and adjust the output frequency to something a LCD or VGA CRT monitor can understand.
That's not what's happens with a "dumb" old scandoubler/flickerfixer. Even the best of the old ones.