The only GPH console is the GP2X. GPH was formed out of Gamepark because of differences in opinion on the direction the next console should take--with GPH favoring a more open-source, homebrew platform and Gamepark wanting a more commercial system (like the PSP and DS).
I believe that all of the XGP models will be open in the sense that software can be made for it by individuals, yes. The focus for the XGP will be high quality 3D and commercial games. XGP Kids seems to basically be a GP32. I'm confused about the XGP mini.. it runs GP32 bios (or a bios that looks identical to it), but it's not supposed to be compatible with GP32 software.
I'm going to be looking into this as I'm working on a major update for my Gamepark newbie site, but it would be nice if someone could confirm or correct what I said.
It runs linux, it haves to be.
It uses a magiceyes soc same as gp2x, so they probably also use dig-n-sys wich means they will try to hold it closed, but it will get otu at the end if they are threatened enugh.
Meanwhile it sohuld be quite straightforward to get the gp2x kernel/sdk working for it, the vrender3d shares most stuff with the mmsp2.