Note that these projects all generate baseband composite video signals (e.g., PAL or NTSC, as appropriate for your area). They do not generate signals compatible with HDTV. The bandwidth just isn't going to be there.
I did spend some amount of time working with the Intellasys SeaForth-24 platform to generate green-screen VGA (because I only used one of the two DACs; note that the 40-core chip has 3 DACs) by "racing the beam". Unfortunately, Intellasys is really faltering in the market, and it's unlikely anyone anywhere will see another of these chips.
It looks like I have a collector's item, and as such, I'm keeping it firmly in the anti-static bag for posterity.