Re: Linux
Information about installing Linux was (somewhat quietly) added to the support website:
https://support.planetcom.co.uk/index.php/Linux_Flashing_Guide
(and see also: https://developer.planetcom.co.uk/)
As it is a little bit of a fiddly process to reflash/install, I think that quite a few people are still waiting for others to have a go first(!), and I think that Planet Computers are more hoping that the user community will take up the baton for managing Linux for the Gemini.
I understand that, unfortunately, the chipset in the Gemini isn't the most Linux-friendly, which doesn't help matters much, but at least it showed that it was possible, if not ideal.
I do very much hope that Planet have taken this consideration on board for future devices, and that they have taken great care to choose the hardware for the Cosmo very carefully, to avoid any similar compatibility problems occurring again.