It's possible to use the internal DMA2d "Chrom-Art Acceletor" with a Colour Look Up Table (CLUT) down to 4 bits per pixel, giving 480x272x4/8=65280 bytes for 16 selectable colours (in L4 mode) or 2 colors with Alpha (in A4 mode).
This, given the 320kB (+change) on a 746NG gives some elbow room also for double buffering, but using the internal RAM controller is no problem, if you get the Disco.
The 746 Disco is definitely an interesting board (I've got two
, but one was complimentary), though it might pack more stuff than what you are looking for: the external connectivity is a bit limited by the number of IOs used for onboard peripherals.
Check the revision of the processor and the relevant errata. I got mine with one of the early masks (and longish errata).
The display mode is fixed: only RGB interface can used, no SPI or bus mode, in case you were interested.
You can also follow an
online MOOC on the ST site that uses it. IIRC, the goal of the exercises its to design a (toy) scope.
A cheaper alternative could be the 429 Disco, with its much smaller display (can be set to all the supported modes).