It looks like the video chip, the TEA1002 takes in RGB and Sync, and outputs composite video. Take your choice which one you'd prefer. You may need to buffer the outputs, so they'll provide a bit more power. Maybe someone could help with an easy transistor or LM318 circuit... similar to the mods for other consoles.
On version 2, yes - the video circuit is done in discrete parts on the version 1 and of course the Grundig version is an entirely different beast (but that version of the console is scarce anyway since it plugged into a special RGB port only found on ancient Grundig TV sets).
IMHO composite will be fully sufficient - these old consoles' video doesn't have that much to gain from RGB (as opposed to higher resolution computers like the Atari ST and Amiga - composite is much worse than RGB esp. in 80 column modes on these machines).
Yes, I am mainly searching for a buffer circuit to have standard voltage for the composite line. For audio, a protective capacitor should suffice - as on the VCS.
BTW, this family of consoles was also sold "down under", e.g. as the "Fountain Force 2".