Is it because virtually nobody buys on GOG so devs prefer to ignore here

Well, enough people are buying to have games released on GOG. It's just that we are so outnumbered by Steam users, and GOG can't throw money at developers like Epic. If you shop on GOG, you should accept that steam comes first.

I don't mind waiting for updates. I do mind when they start abandoning the GOG version. It's slap in the face to any GOG users that supported the Dev

So how finished is v1.0's 'finished'? I haven't been keeping up with every patch, but the last time I looked the past few patches seem to have added a lot of "gameplay" content but the main plot still felt only 5-10% complete. Then suddenly it's done?

it is done. there is a full path now up to animals as the last stage, and there is a quest to leave the planet in the end.

I think its just as finished as launching a rocket in Factorio feels like. It's closure but not the end. Discovering the secrets left by the wardens felt more interesting than the end itself tough.
I also im not convinced its the dev's to blame here: the game updated and i finished both sides of the story already. I'm more inclined to believe it's gog not caring about prepping a release post, wether because wednsday and thursday schedule was pretty full of news, or whatever else reason.

Would love to see the demo here.

New Planet Announcement: Humble

"On the 9th October, a fresh start in a brand new world of Planet Humble awaits The Planet Crafter players! In this new DLC, players can scout this unknown land, discover its story, novelties and secrets and accomplish, once again, the task to terraform an entire world and make it viable for humanity! Survive, gather resources, and build your base. Then, generate oxygen, warmth, and pressure to create a brand new biosphere."

We are the 9th October, but I can't find where to buy the Humble DLC for Planet Crafter on GOG ? It's available on Steam ... :-/

Just the usual GoG release delay, I reckon.
Could help to poke the devs and/or the publisher and remind them that the GoG version of The Planet Crafter exists.

It's happened with upgrades, but makes no sense when they're charging for the DLC. Either they don't need the $$$, or they're hoping we all go and buy the main game again on Steam + the DLC...would be nice if they let us know if/when we can buy on GOG.